IAU Symposium 221	UNSW
	Star Formation at High Angular Resolution

IAU01309 A NEW DIAGNOSTIC FOR INFERRING THE IMF OF YOUNG CLUSTERS
Presenter: Babar Ali
A stellar Initial Mass Function (IMF) diagnostic is presented based on the Number-Ratios (NRs) of stars in three luminosity bins centered at absolute K-band magnitudes of 1.5, 3 and 5 mag. Two NRs are calculated: R1, based on the two high luminosity bins, and R2, based on the two low luminosity bins. Theoretical Luminosity Functions, LFs, (for a given IMF and a set of pre-main sequence evolutionary tracks) are used to estimate of the effects of both the underlying IMF and the ages of cluster members on these NRs. For a given IMF, the range of values for R1 and R2 are found to be well constrained for both coeval and non-coeval clusters. However, significant overlap exists between values derived from different IMFs. Thus, while the NRs from a single cluster can be consistent with several different underlying IMFs, the values from several clusters can nonetheless be used to investigate: (1) is the IMF of the very young embedded clusters the same?, and (2) is the IMF of these clusters consistent with the solar neighbourhood IMF. I will discuss the diagnostic as well as present some results.

IAU00962 COLLAPSE OF MAGNETIZED, ROTATING, TOROIDAL CLOUDS
Presenter: Anthony Allen
Models of molecular cloud cores have been proposed by Frank Shu and Zhi-yun Li. These models have been used as initial states for magnetohydrodynamic collapse calculations to study the dynamics of the early stages of star formation. Implications about accretion rates, outflows, and angular momentum transport will be summarized. Synthetic maps and spectra generated from simulation data will be shown.

IAU01521 GAS, MASSIVE STARS, AND THE STRUCTURE OF SPIRAL ARMS
Presenter: Ronald J Allen
The role of stellar density waves in organizing massive star formation is a central feature of density wave models of spiral structure in galaxy disks which were developed by Lin, Shu, Roberts, and others more than 30 years ago. High resolution radio continuum and HI imagery provided some of the most compelling cases for the close relation between gas and the birthplaces of massive stars in spiral arms in those early days. However, in spite of the general agreement with the models, some of the highest resolution data revealed annoying differences between the expected and observed locations of various gas and dust spiral tracers. In the meantime, improvements in instrumentation have continued, and we can now add high-resolution CO and space-based Far-UV imagery to the arsenal of observational techniques available. This greatly enriches the range of physical phenomena which can be included in the models for the interplay between massive stars and the various physical phases of the ISM in and between spiral arms. I will discuss some of the recent results in terms of a picture involving large-scale photodissociation of H2 and systematic changes in the physical state of the gas as the ISM moves through a spiral arm.

IAU02084 OBSERVING YOUNG STELLAR CLUSTERS WITH SIRTF
Presenter: Lori Allen
Near-IR surveys have demonstrated that most stars form in groups and clusters. To understand the early evolution of stars in these groups and clusters, it is critical to study disks and envelopes surrounding each individual member using thermal dust emission. However, existing observations rarely provide the sensitivity or angular resolution needed to detect and resolve individual stars at wavelengths greater than 3 microns. The SIRTF observatory will provide an unparalleled means for efficiently mapping entire clusters with high sensitivity and angular resolution in the thermal infrared. We describe such a program undertaken with Guaranteed Time Observations by the IRAC instrument team. With SIRTF we will survey 36 regions at distances of 150 pc to 1 kpc at wavelengths of 3-24 microns, with the sensitivity to detect objects below the hydrogen burning limit. Combined with 2MASS and data collected on recent observing campaigns on 2 to 6 meter class telescopes, these data will provide a new inventory of protostars and proto-planetary disks in the nearest kiloparsec.

IAU02012 NIR SUBARCSEC IMAGES OF W49A: UNCOVERING THE BEAST
Presenter: Joao Alves
We present subarcsecond J, H, and Ks images (FWHM ~ 0.5‘‘) of an unbiased 5’x5’ (16 pc x 16 pc) survey of the densest region of the W49 giant molecular cloud. The observations reveal 4 massive stellar clusters (with stars as massive as ~120 M¤), the larger (Cluster 1) about 3 pc East of the well known Welch ring of ultra-compact HII regions. Cluster 1 is a) extincted by at least AV > 20 mag of foreground (unrelated and local) extinction, b) has more than 30 magnitudes of internal inhomogeneous extinction implying that it is still deeply buried in its parental molecular cloud, and c) is powering a 6 pc diameter giant HII region seen both at the NIR and radio continuum. We also identify the exciting sources of several UC~HII regions. The census of massive stars in W49A agrees or is slightly overabundant when compared with the number of Lyman continuum photons derived from radio observations. We argue that although the formation of the Welch ring could have been triggered by Cluster 1, the entire W49A starburst region seems to have been multi-seeded instead of resulting from a coherent trigger.

IAU02016 THE STRUCTURE OF MOLECULAR CLOUDS FROM PC TO AU SCALE
Presenter: Joao Alves
We present results from powerful new method to study the structure of dense molecular clouds on an unprecedented column density range of 0.5 <Av < 50 magnitudes (1021 < N < 1023 cm-2) over physical scales of pc to AU using a combination of 2MASS and VLT data. In this talk I will review the method, describe the results obtained so far, and point to the wonderful opportunities offered by future facilities to study the unsolved problem of the initial conditions to star formation.

IAU00359 YOUNG STAR CLUSTERS: LIGHTHOUSES IN THE DARK
Presenter: Peter Anders
Star cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. Young clusters are observed to form in a variety of such galaxies, a substantial number resembling the well-studied globular clusters in mass and size. Due to the high angular resolution instruments available at present and in the near future, such young clusters can be observed up to much further distances and in more detail, than previously possible. Clusters in the inner parts of bright galaxies and along tidal tails are studied (e.g. "Tadpole" galaxy). The determination of precise radii and masses is crucial for survivability estimates. By studying young clusters in merger remnants and peculiar galaxies, we can learn about the violent star formation history of these galaxies, and about galaxy formation and evolution. We will present a new set of evolutionary synthesis models, specially developed to account for the gaseous emission of presently forming star clusters, and a new tool to compare large model grids with multi-colour observations. First results of newly-born clusters in mergers and starburst galaxies are presented and compared to the well-studied old globulars, and interpreted in the framework of galaxy formation / evolution.

IAU01860 FRAGMENTATION AND KINEMATICS OF THE NGC2068 PROTOCLUSTER
Presenter: Philippe André
Understanding the formation of protoclusters and the origin of stellar masses is a major open problem. Here, we present the results of new, high-resolution millimeter mapping observations of the NGC2068 protocluster in Orion B, taken with the IRAM 30m radiotelescope and Plateau de Bure interferometer. The protocluster includes about 30 prestellar condensations whose mass distribution is consistent with the stellar IMF, suggesting they are the direct progenitors of individual protostars/systems. Observations of lines such as N2H+(1-0) and HCO+(3-2) with the 30m telescope indicate that the condensations are gravitationally-bound, largely devoid of turbulence, and sometimes already collapsing. The relative motions measured between objects on scales ranging from ~2000 AU to ~ 0.5 pc with the two IRAM instruments do not seem to be consistent with strong dynamical interactions, pointing to separate collapse onto essentially independent condensations. Taken at face value, these findings are at variance with models in which the dynamics of protoclusters plays a key role in shaping the distribution of stellar masses. They rather support a “kernel-type” scenario of “decaying turbulence” on small scales.

IAU00898 THE INTERIOR STRUCTURE OF THE G31.41+0.31 HOT MOLECULAR CORE
Presenter: Esteban Araya
We present interferometric images at 7mm and 3.6cm with a resolution of 1500 AU of the G31.41+0.31 Hot Molecular Core. Our observations show an elongated structure which is oriented perpendicular to the bipolar flow observed by Olmi et al. (1996). If the 7mm emission is entirely due to dust, then the total mass in this structure is on the order of 500 solar masses, which implies densities of order 1010 cm-3. The 3.6cm emission is unresolved and coincident with the 7mm peak, and likely marks the position of the central object. We discuss the elongated structure in terms of an accretion disk scenario, as well as a binary scenario. This work is partially supported by Research Corporation grant Nr. CC4996 and NSF grant AST-0098524.

IAU00990 CO DEPLETION AND DEUTERIUM FRACTIONATION IN PRESTELLAR CORES
Presenter: Aurore Bacmann
We present here the results of a search for the doubly deuterated form of formaldehyde, D2CO, in a sample of pre-stellar cores. D2CO was detected in most cores and the [D2CO]/[H2CO] ratio was found to lie around 1-10%. These deuteration levels are similar to those measured in low-mass protostars, providing convincing evidence that D2CO forms during the cold and dense pre-collapse stage and later desorbs when the gas warms up in protostars and is not a gas phase product of the warm protostellar environment. The cores are affected by the freezing out of CO onto the grains and we find that the objects with the highest CO depletions also have the largest [D2CO]/[H2CO] ratios, supporting the theoretical prediction that deuteration increases with increasing CO depletion. Though gas-phase chemical models can reasonably well account for the relative deuterium fractionation, discrepancies with the observations such as oxygen depletion and ionisation fraction need further investigation.

IAU02306 A CENSUS OF MEDIUM-MASS STAR-FORMING REGIONS WITHIN 1 KPC
Presenter: Peter J Barnes
We have used 13CO to associate kinematic distances for a sample of prospective medium-mass star-forming regions in the southern Milky Way. This complements the equivalent northern survey already completed, and we present a valuable new source list for galactic star formation studies, comprising dozens of previously unrecognised such regions. We also present preliminary results of maps of C18O, CS, and/or NH3 emission from these sources, and analysis of these sources' spectral energy distributions.

IAU02710 AMMONIA AND 1MM CONTINUUM MAPS OF MASSIVE DENSE CORES
Presenter: Peter J Barnes
We present new ATCA and SEST observations of medium- and high-mass star forming regions in the Milky Way. The dense molecular cores in these regions were observed in the NH3 (1,1) line at 24 GHz with the new 12mm receiver system on the Australia Telescope Compact Array, and represent some of the first maps of their kind in the southern hemisphere. Many sources show bright, complex emission that varies in position across the line. The 1mm dust continuum emission was also mapped for the first time in many of the same cores, using the SIMBA receiver at SEST. We compare the emission in these two tracers, and assess recent theoretical and observational results that show they should both correlate with the total column density in the cores.

IAU02746 A TIDALLY INTERACTING DISK IN THE YOUNG TRIPLE SYSTEM, WL20
Presenter: Mary Barsony
Combining high angular resolution data from multiple wavelengths has proven to be the crucial factor enabling the discovery of a tidally interacting disk in the WL20 triple system. WL20 is located in the nearby Rho Ophiuchi clouds. Its components have angular separations of 3.17 arcseconds (400AU) in projection E-W, and 2.25 arcseconds (280AU) along a due N-S axis. Sub-arcsecond angular resolution imaging photometry from 1.65 microns to 24.5 microns shows two components exhibiting spectral energy distributions (SEDs) characteristic of T-Tauri stars. However, the third component, WL20S, shows the SED of a self-embedded (Class I) protostar, typically associated with an earlier evolutionary stage than its companions. This age discrepancy is resolved by combining high-resolution millimeter dust continuum maps (obtained with the Owens Valley Radio Observatory's millimeter array) with spatially-resolved near-infrared spectroscopy for each component. The dust continuum images show a warped, disk-like structure centered on WL20S, possibly encompassing WL20W. The near-infrared spectra show two late-type photospheres for the T-Tauri components (K7 for WL20E and M0 for WL20W), with identical values for the continuum veiling (rK=0.2). However, whereas AV=16.3 to the T-Tauri components, WL20S is seen through an additional AV=25!

IAU02561 MULTIPLICITY OF OUTFLOWS IN MASSIVE STAR FORMATION
Presenter: Henrik Beuther
Plateau de Bure Interferometer high-spatial resolution CO observations combined with near-infrared H2 data disentangle at least seven (maybe even nine) molecular outflows in the massive star-forming region IRAS 19410+2336. Position-velocity diagrams of the outflows reveal Hubble-like relationships similar to outflows driven by low-mass objects. Estimated accretion-rates are of the order 10-4 M¤/yr, sufficiently high to overcome the radiation pressure and form massive stars via disk-accretion processes. The single-dish large-scale mm continuum cores fragment into several compact condensations at the higher spatial resolution of the PdBI which is expected due to the clustering in massive star formation. While single-dish data give a simplified picture of the source, sufficiently high spatial resolution resolves the structures into outflows resembling those of low-mass star-forming cores. We interpret this as further support for the hypothesis that massive stars do form via disk-accretion processes similar to low-mass stars.

IAU00161 EMISSION LINE OBJECTS IN MASSIVE STARFORMING REGIONS.
Presenter: Arjan Bik
Near-IR images and high resolution VLT/ISAAC spectra have revealed a population of massive young stars, deeply embedded in Ultracompact HII regions. These objects show no photospheric lines, but are characterized by a strong emission line spectrum. The broad hydrogen emission lines probe high velocity ionized material originating very close to the star, likely from a rapidly rotating disk or stellar wind, than from a dense HII region. A number of these sources have a faint radio counterpart. The radio emission is probably produced by a stellar wind, or is due to free-free emission from the circumstellar disk. CO first overtone bandhead emission has been observed in some of these objects. The CO emission originates in high temperature gas, that must be sufficiently shielded from the massive star's UV-radiation field. Are these objects massive Young Stellar Objects possessing a remnant accretion disk? Or is the emission produced by a disk induced by rapid rotation of the central star as in Be stars? The shape of the mid-infrared spectral energy distributions depends on the physical nature of the disk. We present new mid-infrared observations and discuss the nature of the emission line stars in the context of star formation.

IAU01009 INTERFEROMETRIC STUDIES OF MASSIVE STAR FORMATION
Presenter: Joseph R Birks
Young high-mass protostars are often discovered by the detection of a radio-bright UCHII region. However, once the UCHII region has formed, the star is already relatively evolved and the opportunity to observe the earliest phase of the formation processed has passed. Recent work by Sridharan et al. (2002) has identified a sample of bright sources that have similar dust temperatures and luminosities to sources with UCHII regions, yet have no UCHII region of their own. Further selection techniques have provided a promising sample of very young high mass stars. As a follow-up to SCUBA observations of the whole sample, two of the sources that consisted of multiple condensations have been imaged in the J=1-0 transition of N2H+ and HCO+ (5 arc-second beam). All lines were detected and showed the N2H+ emission to be coincident with the peak of the infrared dust emission. The results of this study will be presented. Our high-resolution CO images of G35.2 provide an opportunity to study a rare phenomenon of massive star formation. The data shows interesting shell structure in a bipolar outflow, which is been studied with the aid of a kinematic model currently in development. We will present our findings of this research.

IAU02262 CIRCUMSTELLAR MATTER OF HAEBE STARS FROM SPECTROPOLARIMETRY
Presenter: Karen S Bjorkman
The growing number of available polarimetric instruments, together with a great improvement in the quality of polarimetric data, is opening up improved ways of learning about the circumstellar environments of hot stars, including the pre-main-sequence intermediate mass Herbig Ae/Be (HAeBe) stars. Moderate-resolution spectropolarimetry provides tighter constraints for theoretical models, and can provide unique information about the circumstellar material. Combining polarimetry with traditional approaches such as spectroscopy and photometry, and using improved detailed modelling techniques, allows us to investigate questions about the nature and distribution of circumstellar matter around these stars. Here we present observations of a selected set of HAeBe stars, including UV (from WUPPE) and optical (from HPOL at PBO and WIYN) spectropolarimetry, high-resolution optical spectroscopy (from the Ritter and McDonald Observatories), optical photometry, and near and mid-IR imaging photometry (from MIRLIN at IRTF). We discuss the implications for the circumstellar geometries of these objects.

IAU02267 MODELING THE SED AND POLARIZATION OF HERBIG AE/BE STARS
Presenter: Jon E Bjorkman
Dust is the dominant opacity source controlling the SED produced by the envelopes of low mass YSOs. However, unlike their lower-mass counterparts, the intermediate mass Herbig Ae/Be stars are hotter, and they produce significant amounts of ionizing radiation. For this reason, the dust will be destroyed in the inner parts of the envelope, where the dominant continuum opacity becomes electron scattering and hydrogen bound-free and free-free absorption. To model observations of Herbig Ae/Be stars, we have modified our 3-D Monte Carlo radiation transfer code to include these gas opacities. In addition to calculating the radiative equilibrium temperature, which controls the presence or absence of dust, this code also calculates the full NLTE ionization equilibrium and level populations of hydrogen. We present models of the SED and polarization produced by the accretion disk of Herbig Ae/Be stars, both with and without an infalling envelope.

IAU01996 TRACING PROTOSTELLAR EVOLUTION VIA INFRARED SPECTROSCOPY
Presenter: Geoffrey A Blake
The energetic phenomena associated with protostars alter the physical and chemical state of the material in the clouds, envelopes, and disks that surround them. In particular the structure and composition of icy mantles on dust grains are expected to be strongly influenced by processes such as thermal heating, ultraviolet irradiation, cosmic rays, and shocks. We will discuss the evidence for these processes by analyzing observations of infrared ice bands obtained with the NIRSPEC spectrometer at the Keck II telescope. The unprecedented sensitivity and spectral resolution of Keck/NIRSPEC allow a detailed analysis of the band profiles of solid CO and, for the first time, 13CO, which sensitively trace the solid state environment and thermal history of the ices toward high and low mass protostars. From more evolved sources, intense CO emission is observed that traces the physical and chemical state of the gas in the terrestrial planet-forming region (0.5-3 AU) of circumstellar disks. The M-band emission is very sensitive to small amounts of gas, and may provide an excellent means of tracing the gas dissipation time scales associated with disk dispersal and/or planet formation.

IAU01997 1-3'' APERTURE SYNTHESIS OBSERVATIONS OF CIRCUMSTELLAR DISKS
Presenter: Geoffrey A Blake
Single dish and millimeter-wave interferometric imaging of disks of gas and dust surrounding several young T Tauri and Herbig Ae/Be stars have dramatically improved our understanding of disk physical and chemical structure. Such observations contribute to a more comprehensive understanding of star and planet formation. In particular, comparison of disk properties with those of comets and Kuiper Belt objects is invaluable in understanding our own Solar System in its infancy. Here we report on the results of a CN/13CO and HCN/HCO+ survey of Herbig Ae and T Tauri star disks using the Owens Valley Millimeter array. Supporting observations of deuterated species in circumstellar disks are also reported. The observed spectral line intensities and, in cases where the signal-to-noise is high, the radial distribution of the emission are modelled via 2D Monte Carlo radiative transfer codes, which results in an accurate assessment of the conditions in the outer disk. The derived chemical compositions of the disks are compared to those obtained via chemical models and those observed for molecular clouds, hot cores, comets and solar system objects.

IAU02070 DISKS AROUND TW HYA AND HD 100546 IMAGED AT 3.4 MM WITH ATCA
Presenter: Tyler L Bourke
We present observations of the young stars TW Hya and HD 100546 made with the ATCA at 89 GHz with ~2" resolution and ~3mJy continuum sensitivity. Compact thermal dust continuum emission is detected from disks surrounding both stars. HD 100546 shows hints of additional extended emission, presumably a residual protostellar envelope, also visible in scattered light at optical wavelengths. For TW Hya, HCO+ J=1-0 line emission from the circumstellar disk is detected and spatially resolved. The observed size and intensity are in good agreement with model calculations based on an irradiated disk with substantial depletions constrained previously from higher-J transition single dish data.

IAU00445 BINARY BROWN DWARFS: CLUES TO THE SUBSTELLAR FORMATION.
Presenter: Herve Bouy
We present the results of observations of a sample of binary brown dwarfs using the high angular resolution provided by HST WFPC2, ACS and STIS and VLT/NACO. Pushing the limits of these instruments, we manage to resolve objects as close as 0.030”.

IAU01335 THE EYE OF THE TORNADO - AN ISOLATED HMPO NEAR THE GC
Presenter: Michael Burton
We present infrared (AAT, UKIRT) and radio (VLA, SEST) observations of the Eye of the Tornado, a compact radio source apparently near the head of the Tornado. The near-IR Brackett g and helium lines are broad (FWHM 40 & 30 km/s respectively) and have a line centre at -250 km/s Vlsr. This corresponds to a feature at the same velocity in the 12CO J=1-0 line profile. The kinematic velocity derived from rotation then places the Eye at the distance of the Galactic centre (ie 8,500 pc) and separated (probably foreground) from the Tornado nebula. Four knots of emission seen in the Brackett g line and at 6 & 20 cm. Together with the flat radio spectral index, we confirm that the Eye is an HII region, but that it is also embedded within a dense molecular core. The knots are UCHII regions, and the core contains a luminous (2 x 104 L¤), embedded, massive proto-stellar source.

IAU01313 MAPS AND MAGNETIC FIELDS OF OH EXCITED STATE MASERS
Presenter: James L Caswell
Masers delineate sites of massive stars shortly after birth. The masers provide a tool to probe physical conditions in the star forming region (SFR), offering high resolution spatial and kinematic information, magnetic field strengths, and distance estimates, all of them crucial parameters in understanding star formation itself. We present studies of excited OH using the Long Baseline Array of the Australia Telescope National Facility. For each target, observations of both the 6035- and 6030-MHz hydroxyl transitions are obtained simultaneously (within a single continuous 8-MHz band) and yield a series of maps with high spatial resolution, at velocity spacing 0.2 km/s, in both senses of circular polarization. These reveal many maser spots scattered over several arcsec. Pairs of right and left circularly polarized spots with the same position, but offset in frequency (velocity), reveal Zeeman splitting. At several spots, Zeeman pairs at both 6035 and 6030 MHz are seen, with both transitions indicating the same value of magnetic field and the same (central) kinematic velocity. The morphology and kinematics can be compared with that of maser emission from other masing transitions of OH, and of methanol at 6668 MHz.

IAU02323 DUST GRAINS IN C-TYPE SHOCK WAVES.
Presenter: Jacqueline F Chapman
Shock waves travelling through molecular clouds exhibit a multi-fluid structure such that the charged and neutral components can be treated as separate and interpenetrating fluids. Previous shock models include 3charged species in their calculations: ions, electrons, and a single grain species to represent the population of dust grains. However, interstellar dust has a broad distribution of grain sizes, each with a different charge, mass, and internal density. The size distribution and nature of the dust grains in turn depends upon the astrophysical environment in which they are found. I investigate the role and behaviour of dust grains in C-type MHD shock waves in weakly ionised, dense molecular clouds. I include the grain size distribution, and solve the MHD equations for steady, plane parallel, multi-fluid shock structures. I compare shock profiles for different initial grain size distributions, grain charging assumptions, and pre-shock magnetic field strengths and densities. I also present comparisons of the grain species fluid variables which are dependent on grain size.

IAU01262 THE OBSERVATIONS OF IR-EXCESS CLOUDS AND THE POLARIS FLARE
Presenter: Seungyoup Chi
We present two interim observation results of the survey for molecular clouds toward far-IR excess clouds in high galactic latitude and the observations toward dense region in the Polaris Flare searching for gravitationally bound cores, which are carried out using SRAO(Korea) 6m telescope. First, we have been observing 14 IR excess clouds of Reach et al.(1998) in northern hemisphere. All of 14 IR excess clouds were mapped in 12CO(J=1-0). We could detect CO emission from 3 IR excess clouds and expect to detect CO emission from about 2 objects more. The dust temperatures of these 3 IR excess clouds with CO emission are all around 17K (colder ones) and the amount of IR excess are about 1 kJy, suggesting that the colder clouds are well shielded from external UV radiation. And for the clouds without CO emission, it is a question whether the region is metal deficient or another phase of Carbon in it. Second, we have mapped the southern region of the one of high-latitude molecular clouds complex, the Polaris Flare, in 12CO(J=1-0; 4' grid) and 13CO(J=1-0; 2' grid). We could find the clumpy structures and expect that there are several gravitationally bound cores and cores under infall motion.

IAU02657 HIGH RESOLUTION EVOLUTIONARY STUDIES OF THE XZ TAURI OUTFLOW
Presenter: Deirdre Coffey
We report on multi-epoch HST/WFPC2 images of the XZ Tauri binary, and its outflow, covering the period from 1995 to 2001. Data from 1995 to 1998 have already been published in the literature. Additional images, from 1999, 2000 and 2001 are presented here. These reveal not only further dynamical and morphological evolution of the XZ Tauri outflow but also that the suspected outflow source, XZ Tauri North has flared in EXor-type fashion. In particular our proper motion studies show that the recently discovered bubble-like shock, generated by the XZ Tauri jet, is slowing down (its tangential velocity decreasing from approximately 170 km/s to 120 km/s). We also present simulations of the outflow itself, with plausible ambient and outflow parameters, that appear to reproduce not only the dynamical evolution of the flow, but also its shape and emission line luminosity.

IAU02675 ROTATION OF JETS FROM T-TAURI STARS NEW CLUES FROM HST/STIS
Presenter: Deirdre Coffey
Whether jets from newly forming stars rotate is a fundamental question in star formation research. Theoretical models propose jet rotation as a means of removing angular momentum from the young star and disk system, thus allowing accretion. While widely accepted, this idea has not yet been tested observational due to the high resolution requirement of examining jets close to their launching point. Previous findings from the Hubble Space Telescope Imaging Spectrograph (HST/STIS) and Owens Valley Radio Observatory (OVRO) give indications of same sense rotation of the jet (Bacciotti et al 2002) and disk (Testi et al 2002), respectively, of T Tauri star DG Tau. We report preliminary findings from HST/STIS data for 3 of 8 sources in a current survey to establish conclusively whether protostellar jets rotate. The results were positive, yielding evidence of radial velocity differences about the axis at the base of all three jets of up to 20-30 km/s.

IAU01765 OH MASER DISCS AT THE CENTRE OF BIPOLAR MOLECULAR OUTFLOWS
Presenter: Raymond J Cohen
Ten OH 18-cm maser sources associated with bipolar molecular outflows were mapped using MERLIN, with angular resolutions of 0.25 and 0.13 arcsec. In each case the masers were found to lie at the centre of the outflow. The OH masers have velocity ranges of up to 30 km/s and are among the most variable known. There is strong circumstantial evidence that the masers trace the inner regions of a dense molecular disc orthogonal to the bipolar outflow. The evidence includes elongation of the maser distribution and velocity gradients indicative of overall disc rotation. The typical disc radius is 3000 AU, while the typical enclosed mass of 30 solar masses is more than sufficient to account for the far infrared luminosity. The magnetic field inferred from Zeeman splitting of the OH lines is typically 5 mG. In some of the sources polarization measurements of the OH masers suggest a twisted magnetic field configuration which includes a toroidal component around the disc.

IAU00339 STAR FORMATION ENVIRONMENTS: OBSERVATIONS AND MODELLING
Presenter: Jose Carlos Correia
We present far-infrared (FIR) continuum observations of Young Stellar Objects performed with the Long-Wavelength Spectrometer (LWS) on-board the Infrared Space Observatory (ISO). We also report 450 and 850 micron mapping observations done with SCUBA at the JCMT. We combined these observations with IRAS data in order to construct complete spectral energy distributions of the sources. A spherically symmetric dusty envelope model was used to reproduce the SEDs and to characterize the circumstellar matter around the objects. We call attention to the fact that when using this kind of models, one needs spatial information about the objects in order to distinguish between different possible fits to the SEDs. The need for high angular resolution observations is also pointed out if one wants to constrain with confidence several parameters of the model.

IAU02062 THE IMF OF NEWLY DISCOVERED EMBEDDED CLUSTERS
Presenter: Angela Cotera
We have observed five newly discovered embedded stellar clusters in the near-infrared (JHK) on the 6.5m MMT using the PISCES camera. PISCES uses a 1024x1024 HAWAII array with a 0".18 pixel scale on the MMT. Three more clusters are scheduled to be observed on the 4m AAT in June. We located the clusters by searching the 2MASS point-source catalogue for stellar density enhancements with red near-infrared colours, indicating embedded clusters. The 2MASS search was targeted at regions of radio and mid-infrared emission suggestive of star formation regions. The clusters span a range of Galactic environment and cluster masses, including one toward the Galactic anti-center that may rival the well-known Arches Cluster (located in the Galactic Center) in richness. The heavy reddening of the clusters (AV ~ 10-20) and the presence of massive stars indicates that they are quite young, possibly still forming massive stars. We will present preliminary initial mass functions for the clusters based on the photometric data as part of a project to obtain IMFs for stellar clusters spanning a range of environments and stellar densities to see if any variation in the IMF with Galactic location can be determined from these rich clusters.

IAU02371 HST/NICMOS HIGH RESOLUTION IMAGING POLARIMETRY OF YSOS
Presenter: Angela Cotera
We have obtained high resolution polarimetric images of the Young Stellar Objects (YSOs) Parsamian 21 and Reipurth 50 with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard the Hubble Space Telescope (HST). The observations were made with the polarizers on NIC2, which has a pixel scale of 0.076", and provides observations at a wavelength of ~2 microns. The unprecedented resolution and sensitivity enables us to analyze in detail the distribution of polarized light, clearly revealing the source of the scattered light and a wealth of structure. The polarized light also enables a study of the distribution of dust around these objects, allowing us to address whether any density gradients are seen within the regions. In the case of Re 50, the polarized light shows a significant amount of dust not associated with the scattering source, indicating additional phenomena unrelated to the primary stellar source.

IAU02094 RAPID CHANGES IN THE STRUCTURE OF THE BN OBJECT
Presenter: William C Danchi
The BN/KL region in Orion radiates about 105 L¤ and displays prominent bulk mass flows. The Becklin-Neugebauer object (BN) is an early-type massive star that is the most prominent source in the region at near-infrared wavelengths. We used the LWS instrument on the Keck-I telescope to make 12.5 um and 18.7 um which reveal unusual new detail in the wings of the stellar source. We have discovered a previously unknown infrared counterpart to the centimetre-wave radio "companion" located only 1.5 arcsec west of BN. This secondary object (a.k.a. B2) is present at both epochs and does not appear to move, on 0.1 arcsec scales. We also see changes in the shape of BN, which may a consequence of "bullets" of material being ejected. These bullets are only detected at 18.7 um. Such changes have not been seen before at infrared wavelengths. Careful inspection of images for BN and a point-like standard star, obtained within a few minutes of each other, indicates that the putative bullets are not imaging artifacts. We explore several possible scenarios to explain the changes in the mid-infrared image of BN on one year time scales.

IAU02549 PROBING EMISSION-LINE REGIONS AT THE BASES OF YSO JETS
Presenter: Chris Davis
We will present high-spectral-resolution near-IR observations of the Forbidden Emission Line (FEL) and Molecular Hydrogen Emission Line (MHEL) regions at the bases of collimated jets from a dozen or so Class I protostars. Kinematics and simple spectro-astrometric techniques are used to characterize these emission-line regions, so that their properties can be compared with those of FEL regions and small-scale

IAU02658 EARLY RESULTS FROM THE UKIRT IMAGING SPECTROMETER, UIST
Presenter: Chris Davis
New opportunities for high angular resolution observations with the 4m UK Infrared Telescope (UKIRT) have been afforded by the installation of a new imaging spectrometer, UIST. This instrument is capable of observations in the near-infrared wavelength region (1-5microns) and offers imaging at two plate scales (0.06arcsec and 0.12arcsec), spectroscopy in two resolution regimes (low: R~1000 and moderate: R~3500 for a 0.24arcsec slit) and a deployable integral field mode giving two dimensional spectroscopy over a 3.3arcsec x 6arcsec field. The combination of wavelength coverage and versatility of the instrument was exploited during the commissioning to study a variety of phenomena associated with star formation. We will present some of the early results from UIST as well as highlighting the effectiveness of such a facility class instrument. Imaging of star-forming regions can be rapidly augmented by long slit or integral field spectroscopy of discovered knots and features. Integral field spectroscopy offers the dual advantages of high-fidelity observations of the interaction of stars with their surroundings and the ability to observe small sources with poorly determined astrometry. Future large telescopes will rely increasingly on these technologies to explore star formation in other galaxies at high angular resolution.

IAU01723 PRIMA FOR THE VLTI AND THE OBSERVATION OF ACCRETION DISKS
Presenter: Françoise Delplancke
We will describe the capabilities and current status of the Very Large Telescope Interferometer (VLTI), equipped with its Phase-Referenced Imaging and Micro-arcsecond Astrometry (PRIMA) facility, in terms of observation and characterisation of star forming regions and accretion disks. The resolution of the VLTI in its imaging mode can reach down to a scale of 1AU in the stellar nebular if this one is located at a distance of up to 1kpc in K-band or 100pc in N-band. An image of the accretion disk at such a resolution will allow detecting gaps and surface density fluctuations due to the presence of planets and help constraining models of star and planet formation.

IAU02506 VLTI NIR-INTERFEROMETRIC OBSERVATIONS OF VEGA-LIKE STARS
Presenter: Emmanuel Di Folco
Debris disks around Vega-like stars have mainly been explored with sub-millimeter interferometers or visible and NIR coronagraphs which revealed the presence of cold dust in extended structures from ~20 AU to hundreds of AU from the stars. These optically thin disks are thought to be permanently replenished by comets or asteroids collisions in such forming planetary systems where exoplanets and disk asymmetries have recently been detected. For the first time, interferometric observations in the near-infrared with the VLTI allow to probe the very inner regions of the disks (up to a few AU) where hot dust is supposed to be found. Four of the nearest stars with debris disks (Beta Pictoris, Fomalhaut, Epsilon Eridani and Tau Ceti) have been observed with VINCI, the VLTI commissioning instrument, on various baselines in K and H bands. Their fundamental parameters are measured and compared to those derived from the evolution models. We show how these observations can constraint the stellar photospheres and the presence of hot dust or faint companions in these planetary systems. Finally we discuss the detectability of disks and faint companions around these nearby stars with the future VLTI instruments.

IAU00385 W49A NORTH - GLOBAL, LOCAL, OR NO COLLAPSE?
Presenter: Helene R Dickel
Radiative transfer calculations have been performed in an attempt to fit profiles of several CS transitions(J=2-1, 3-2, 5-4, 7-6) observed towards HII regions A, B, G in the star-forming complex W49A North. Three models were considered: global collapse of a very large (5 pc radius) cloud, localized collapse of smaller (1 pc) clouds and multiple, static clouds. For all three models, it was possible to find combinations of parameters that reproduce the CS profiles reasonably well provided that the component clouds have a core/envelope structure with a temperature gradient. Cores with high temperature and high molecular hydrogen density are needed to match the higher transitions (e.g. J=7-6 with 20" beam). The low density gas needed to create the inverse P-Cygni profile seen in the CS J=2-1 line (with 5" beam) towards HII G, arises from different components in the 3 models. The infalling envelop of G plus cloud B creates the absorption in global collapse, cloud B is responsible in local collapse, and a separate cloud, G', is needed in the case of many static clouds. Research partially supported by the National Science Foundation USA; grants AST90-24503, 93-20239, and96-13999 to the University of Illinois.

IAU01692 HIGH RESOLUTION OBSERVATIONS OF 6.7-GHZ METHANOL MASERS
Presenter: Richard Dodson
We have used the Australian Long Baseline Array (LBA) to produce milli-arcsecond scale images of a number of methanol maser emission sites. All of these sites have linear morphologies at arcsecond resolutions. This result has been taken to infer the existence of circumstellar disks which the maser sites are tracing. Our LBA observations reveal them to be more complex and tend not to support the disk hypothesis. These are the first reported observations of methanol using the S2 recording system and the LBA correlator, a combination which delivers great flexibility for observers.

IAU02598 MOLECULAR SURVEY IN DISCS
Presenter: Anne Dutrey
We have used the IRAM-30M telescope to observe several molecular lines in protoplanetary discs surrounding the T Tauri and Herbig Ae stars: DM Tau, LkCa15, AB Aur MWC480 and HD163296. Several molecules were detected: H2CO, H13CO+, DCO+. In parallel, we have also started to investigate the vertical structure of the discs, taking into account the effects of photodissociation on the abundances of observed chemical species and on the deduced size of the disc. We report in this poster the main results of the observations and a preliminary analysis of the data, together with preliminary results of the modelling.

IAU00140 OH MASERS ASSOCIATED WITH HMPOS
Presenter: Khaled A Edris mahmoud
A search for OH maser emission at 1665, 1667, 1612 and 1720 MHz towards a sample of 217 High Mass Protostellar Objects (HMPOs) candidates is currently underway using the Nancay radiotelescope. The initial results indicate the presence of OH emission towards about 25% of these objects. Analysis and comparisons with other kinds of masers are presented. Imaging one of the objects in the survey, IRAS 20126+4104, with high angular resolution using MERLIN, locate the masers near the centre of the molecular disk previously detected in CH3CN and NH3 observations. The distribution of OH masers has the same elongation and velocity distribution as the disk. Measurements of the strength and direction of the magnetic field of this region are presented. Additional new MERLIN observations of the H2O ands CH3OH masers towards this source are also presented.

IAU01487 A TURBULENT ORIGIN FOR FLOCCULENT STRUCTURE IN GALAXIES
Presenter: Debra Elmegreen
The flocculent structure of star formation in 7 galaxies has an azimuthal Fourier transform power spectrum with a slope that increases from -1 at large scales to -1.7 at small scales. This is the same pattern as for HI gas in the LMC and for dust clouds in galactic nuclei, and it corresponds to the slope of -3 for 2D power spectra that have been observed in atomic and molecular surveys of the Milky Way, LMC, and SMC. The same power spectrum for optical star formation arises in both flocculent and grand design galaxies, which implies that the physical processes are universal. Fractal Brownian motion models that include discrete stars and an underlying continuum of starlight match the observations if all of the emission is organized into a global fractal pattern with an intrinsic 1D power spectrum having a slope between 1.3 and 1.8. We suggest that star formation on large scales is the result of turbulence, and that the turbulent motions are generated by sheared gravitational instabilities which make flocculent spiral arms and then cascade to form clouds and clusters on smaller scales. Support from NSF grant AST-0205097 to B.G.E. is gratefully acknowledged. Observing facilities include HST and CFHT.

IAU00354 FROM DISC WIND MODELS TO OBSERVATIONS OF TTAURI MICROJETS
Presenter: Jonathan Ferreira
Two decades after their discovery, jets from accreting young stars still represent a major challenge for theorists. Several theoretical scenarios have been proposed but only models involving large scale magnetic fields have proved capable of producing self-collimated jets. However, the launching region remains unknown: is it the star, the surrounding accretion disc or their interaction zone? Progresses in high angular resolution offer now the opportunity to test the various proposed models. I will first review the results on magnetized disc winds, based on the only MHD model describing self-consistently these accretion-ejection structures. Then, I will show how the thermal and ionization states of the outflowing matter can be consistently computed, once the dominant heating source has been chosen (ambipolar diffusion, alfven wave damping or some local mechanical heating). A set of observational predictions (emission maps, line fluxes/ratios and line profiles) for selected optical forbidden lines can then be calculated. As an illustration, I will compare these predictions with new sub-arcsecond spectroimaging observations of the DG Tau and RW Aur jets, and discuss the constraints they set on disc winds in T Tauri stars.

IAU01852 IMAGING IN ORION: NAOS-CONICA ADAPTIVE OPTICS ON THE ESO-VLT
Presenter: David Field
Near-infrared observations of line emission from excited molecular hydrogen and in the continuum are reported in the direction of the Orion molecular cloud OMC1, using the European Southern Observatory Very Large Telescope UT4, equipped with the NAOS adaptive optics system on the CONICA infrared array camera. Spatial resolution has been achieved at close to the diffraction limit of the telescope and images show a wealth of morphological detail. Structure is not fractal but shows two preferred scale sizes of 2.4" and 1.2", where the larger scale may be associated with star formation. K-band spectra from selected areas of interest will also be presented.

IAU01868 SHOCKS AND STAR FORMATION IN ORION: FIRST LIGHT WITH GRIF
Presenter: David Field
A new instrument, "GriF", has been used on the Canada-France-Hawaii Telescope to record spatially and velocity resolved images, in the molecular hydrogen v=1-0 S(1) line in the K-band, of a 1'x1' field in the core of the Orion Molecular Cloud, OMC1. Using the PUEO adaptive optics system combined with Fabry-Perot interferometry, diffraction limited spatial resolution of 0.15 arcsec and velocity discrimination of ~1 km/s has been achieved. These data yield graphic images of shocks in OMC1, presenting a level of detail which has not previously been attained. Observed structures suggest that a significant fraction of the regions strongly emitting in molecular hydrogen do so through local, internal shocks, associated with star formation within the clumps of gas involved. Thus the core of OMC1 is revealed for the first time as a region which contains a number of developed protostars.

IAU02337 OBSERVATIONS OF BHR71 USING THE ESO-VLT
Presenter: David Field
Near-infrared observations in both spectroscopy and imaging have been performed, in the K-band, of the Bok globule BHR71, using the Infrared Spectrometer and Array Camera (ISAAC) on the European Southern Observatory Very Large Telescope UT1. Special attention has been given to an outflow region in a direction within a few hundred AU or less of a protostar. Exposures in excess of 5 hours on the object yield a spectrum of molecular hydrogen emission, including a weak continuum. An image of the zone in the S(1) v=1-0 line at 2.121 microns, obtained through the 2 arcsecond slit of the spectrometer, shows that emission is concentrated into a number of unresolved clumps 50-100 AU in diameter. Shock models have been used to show that these clumps are of high density. For comparative purposes, spectra are also presented of a second and much brighter protostar and of a Herbig-Haro object in BHR71.

IAU02342 THE COMPACT STAR FORMING REGION N88A IN THE SMC
Presenter: David Field
We present optical, near-infrared (NIR) images and spectra of the compact, dusty HII region N88A in the SMC. Data were obtained in the visible with the Boller & Chivens spectrograph at the ESO 1.5m telescope and with the infrared spectrometer and array camera (ISAAC) at the VLT-UT1, around 2 microns in 1-0 S(1) molecular hydrogen emission. The latter identified a molecular hydrogen emitting region in and eastward of the two major components of N88. Using long-slit spectra obtained in the 3600-10000 Angstrom range, we have re-determined the key physical parameters of electron temperature and densities of the S++ and O+ zones. The spectral type of the complex exciting source of N88A has been have classified as an O6-O8 V (most likely < O7 V) using He and H lines in the visible and NIR. A comparison with a recent photometric study shows that the V magnitude of the exciting source of N88A has previously been overestimated. The chemical abundances of He, O, N, Ne, S, and Ar, from the emission-line intensities, are also derived and are consistent with the average abundances for SMC HII regions.

IAU00623 MASS FUNCTIONS OF YOUNG STAR CLUSTER SYSTEMS
Presenter: Uta Fritze - V. Alvensleben
At high angular resolution starbursts and post-starburst regions in merging galaxies and merger remnants break up into large numbers of bright compact star clusters to the extent that cluster formation seems to be the dominant mode of violent star formation. Star and cluster formation efficiencies are high, even on large/global scales. Theoretical expectations range from "star formation is an up-scaled universal process" through "star formation is fundamentally different at low-levels compared to starburst environments". Masses and mass functions of star clusters in slowly star-forming and starburst galaxies may hold important clues to resolve this controversy. We use a number of examples to show to what extent evolutionary synthesis models for star clusters of various metallicities - in comparison with observed spectral energy distributions (UV-NIR) of individual clusters - allow to determine mass functions of young and intermediate-age cluster systems. This is not trivial because the luminosity functions of young and intermediate-age cluster systems do not reflect their mass functions due to (i) the strong variations of M/L-ratios over age differences among clusters in extended starbursts (>~100 Myr) and (ii) effects of metallicity and dust. We discuss implications of our results and compare to high-resolution observations of molecular cloud mass spectra.

IAU00968 SUBARU CORONAGRAPHIC IMAGING OF HERBIG AE/BE STARS
Presenter: Misato Fukagawa
The environment around Herbig Ae/Be stars represents an early stage of planet formation around intermediate-mass stars. In order to investigate circumstellar structures of Herbig Ae/Be stars, high-resolution and high-contrast observations are required; the central stars are too bright and the distances are often too far to resolve nearby envelopes, disks, or companions. In order to study their circumstellar environments, we have carried out the near-infrared high-resolution coronagraphic imaging of 10 Herbig Ae/Be stars spanning various ages. The images were obtained with the Subaru 8.2-m telescope and the stellar coronagraphic camera CIAO (Coronagraphic Imager with Adaptive Optics). We detected large-scale envelopes around 2 young Herbig Ae/Be stars, while small-scale circumstellar disks were resolved around 3 old Herbig Ae/Be stars. Several faint nearby companions are also found. We present the properties of each structure, such as their sizes and brightness distributions. The resolved disks extend from the edge of the coronagraphic mask (50 AU) to about 200 AU with no gaps. These optically thick disks are the precursors of debris disks around Vega-like stars. We will discuss the morphological evolution of circumstellar structures around intermediate-mass stars.

IAU00616 THE STRUCTURE OF HIGH MASS PROTOSTELLAR OBJECTS
Presenter: Gary A Fuller
To address many problems regarding high-mass star formation, we must observe the earliest stages of evolution, before the powerful protostar disrupts its natal envelope. We present new HCO+ and N2H+ measurements and 450 and 850 micron observations of a sample of pre-UCHII era high-mass protostellar objects. Through analysis of the dust continuum emission, we measure the mass of the sources, finding a break in the mass distribution; we also calculate the dust grain emissivity, finding an interesting dichotomy in its relationship with submm flux. We model the spectral energy distribution and intensity profile of the submm detections using the radiative transfer code DUSTY, from which we derive envelope density profiles more shallow than those towards low-mass sources. A number of models imply the long and short wavelength flux do not have the same origin. We find tentative evidence that the bolometric temperature used to characterise the low-mass stellar evolution may also be used for high-mass stars. The molecular line observations probe the velocity field in the circumstellar regions and have been analysed to look for evidence of infall of gas towards the forming star.

IAU01933 STAR FORMATION IN THE DISK OF CENTAURUS A
Presenter: Jose G Funes
We present a star formation study in the disk of the nearest giant elliptical galaxy, Centaurus A (NGC 5128). This well studied galaxy is also the nearest AGN, hosting both a supermassive black hole and a powerful radio source. Further yet, Cen A is the nearest galaxy with shells, contains a central dust lane, and boasts a populous globular cluster system. However, little quantitative progress has been realized in recent years on the issue of Cen A's continuing star formation. We present Very Large Telescope (VLT) optical images of the innermost regions of Centaurus A. Deep photometry (B<25) of the sources detected in these BVRI images allows us to make colour-magnitude and colour-colour diagrams. These diagrams reveal a mixture of populations. We identify young stars and blue clusters, plus old globular clusters, embedded in the dusty regions of the NGC 5128 disk. In addition, H-alpha images are used to derive the HII region luminosity function, effectively constraining ensemble characteristics of those clusters formed most recently (within about 10 Myr).

IAU01041 THE GLOBAL STAR FORMATION LAW IN GALAXIES: REVISITED
Presenter: Yu Gao
HCN survey, measure of the total dense molecular gas, in 65 galaxies (Gao & Solomon 2003) has shown that there is a tight linear correlation between IR and HCN luminosities. The correlation between IR and CO, which is used to establish the global Schmidt law in galaxies (Kennicutt 1998), could simply be a consequence of much tighter correlations between IR and HCN and between HCN and CO. This is further demonstrated by the fact that there is a significant correlation between luminosity ratios of IR/CO and HCN/CO, whereas no correlation between IR/HCN and CO/HCN. These results suggest that the global star formation (SF) rate depends more intimately upon the amount of dense gas traced by HCN than the total molecular gas measured by CO, and global SF efficiency (IR/CO) depends on the dense gas fraction (HCN/CO). We further show that the index of Schmidt law varies from 1 to nearly 2 when sample changes from mainly normal disk galaxies to mostly luminous and ultraluminous infrared galaxies (ULIGs). However, the Schmidt law in terms of dense gas appears to be linear (index=1) for all star-forming galaxies, from normal disks to ULIGs.

IAU00655 ISOLATED STAR FORMATION IN THE VIRGO CLUSTER
Presenter: Ortwin Gerhard
VLT spectroscopy has confirmed an isolated compact HII region in the Virgo cluster, located in the diffuse outskirts of NGC 4388 or possibly in intracluster space. Star formation can thus take place outside the main star formation regions in galaxies. This object is powered by a small starburst with an estimated mass of 400 solar masses and age of 3 Myr. From a total of 17 HII region candidates, the present rate of isolated star formation in this Virgo field is small, but this mode of star formation could have been more important at higher redshifts. Such objects are relevant also for possible star formation in Galactic high velocity clouds, for the in situ origin of B stars in the Galactic halo, and for local enrichment by supernovae type II.

IAU02088 MID-INFRARED IMAGING OF ORION BN/KL WITH KECK I TELESCOPE
Presenter: Daniel Y Gezari
We present new images of the Orion BN/KL infrared complex at 4.8, 8.0, 8.9, 9.9, 10.4, 11.7, 12.5, 17.6, 18.1, 20.0 and 22.0 um obtained with the 10-meter Keck I telescope, with typically 0.3 arcsec resolution at 12.5 um. The multi-wavelength observational image data is registered in a stack and a dust emission/extinction model is fitted to the resulting spectrum of each pixel to create a diffraction-limited "image" of the temperature, opacity and luminosity of the emitting dust, as well as the circumstellar and line-of-sight dust extinction. New source structure, temperature, opacity and luminosity detail is seen in the vicinity of IRc2-IRc7. The model results are used to develop a more complete picture of the structure and energetics of the BN/KL infrared complex.

IAU00641 OUTFLOWS FROM YOUNG MASSIVE CLUSTERS IN THE ANTENNAE
Presenter: Andrea M Gilbert
The youngest super star clusters (SSCs) in the merging Antennae Galaxies (NGC 4038/39) drive supersonic mass-loaded outflows from the HII regions in which they are embedded. High-resolution K-band NIRSPEC spectroscopy reveals broad, spatially extended Br-gamma emission in 16 targets. The radial velocity field of young clusters resembles that of the surrounding molecular gas. Simple wind models for the line profiles provide good fits and imply cluster mass-loss rates of up to 1.5 M¤/year and terminal velocities of up to 205 km/s. The emission-line clusters (ELCs) that drive these outflows constitute at least 15% of the star-formation rate in the Antennae, and their high star-formation efficiencies imply that they will evolve into bound SSCs. Comparison with population synthesis model predictions suggests that the youngest ELC outflows, which are driven primarily by stellar winds, very efficiently entrain ambient matter. The cluster winds transfer or dissipate a large fraction of their energy and momentum in a coronal or cool medium that does not emit Br-gamma. ELCs are the individual engines that power galactic-scale superwinds, viewed in their earliest evolutionary stage. About half of the Chandra sources in the Antennae have IR cluster counterparts in which colliding-wind binaries could produce super-Eddington X-ray luminosities.

IAU00976 VLBA IMAGING OF A FLARING 12.2 GHZ METHANOL MASER
Presenter: Sharmila Goedhart
The class II methanol maser G9.62+0.20E has been found to undergo periodic flares at both 6.7 and 12.2 GHz. Single-dish observations at HartRAO enable us to monitor the changing intensity of the maser with high time resolution. However, high angular resolution imaging is necessary in order to understand the underlying mechanism causing the flares. The flare peaking in October 2001 was observed during a series of seven VLBA observations spaced over a period of three months. The images show the progression of the flare, and confirm that there is a time delay in the progression of the flare across the maser spots. This can be used to determine the origin of the mechanism causing the flares.

IAU00940 A CLUSTER OF RADIO SOURCES IN GGD 14
Presenter: Yolanda Gomez
We present sensitive VLA radio continuum observations at 3.6 and 6 cm made quasi-simultaneously toward the star forming region GGD 14. In addition to VLA 1, the previously known compact cometary HII region, a cluster of nine radio sources was found. Most of these sources show variability at radio wavelengths, and their spectral indices are characteristically negative. We propose that gyrosynchrotron radiation from an active magnetosphere explains the emission from almost all the faint compact sources, suggesting that the GGD 14 region harbours a cluster of low-mass, pre-main-sequence stars.

IAU01288 MULTIPLE STAR FORMATION IN ISOLATED CORES
Presenter: Simon Goodwin
We present the results of over 100 simulations of star formation in turbulent molecular cores. Moderate levels of turbulence very often form several stars and brown dwarfs. Most often, a central binary star forms with two unequal components in highly elliptical orbits. Smaller objects are dynamically ejected, truncating their growth and creating a high-velocity, low-mass population.

IAU01816 WINDS AND JETS FROM NEARBY HERBIG AE STARS IN LYMAN ALPHA
Presenter: Carol Grady
High angular resolution spectral imaging of winds and outflows from pre-Main Sequence stars is important in constraining the size and nature of the collimation region. While the proximity of the nearest, pre-main sequence stars makes them the obvious choices for such studies, these objects are typically bright, and require techniques, such as coronagraphic spectroscopy, to optically detect outflows. Lyman alpha observations, for stars with low foreground extinction, offer gains of 100-1000 in the nebulosity to star contrast. We report the detection of spatially extended wind and jet features associated HD 163296, HD 104237, and HD 100546. Both HD 163296 and HD 104237 have bipolar microjets which are resolved at r>7 AU from the star. These objects suggest that the majority of Herbig Ae stars through 6 Myr in age may still be driving jets. In contrast, HD 100546 (t>10 Myr) while showing spatially extended reflection nebulosity, scattered emission lines, and fluorescent molecular hydrogen emission, shows a low velocity wind seen in absorption against the nebulosity in Si III. This wind is accelerated by only -80 km/s in 0.5”.

IAU02541 VLT ADAPTIVE OPTICS OBSERVATIONS OF STARBURST GALAXIES
Presenter: Damien Gratadour
Study of UltraLuminous Infrared Galaxies (ULIRGs) requires high angular resolution, in the range usually provided by adaptive optics. One severe limit is however the lack of visible reference because the nucleus of ULIRGs is extremely absorbed. NACO, the new VLT adaptive optic system, offers the unique capability of wavefront sensing in the infrared, so that, for the first time, it has been possible to servo an AO system on the nucleus of a genuine ULIRG, Arp 220. We present diffraction limited images in the L band and an analysis that aims at discriminating between a point-like AGN or a more extended heating source as a starburst. Another series of results obtained with NACO are presented on the AGN/starburst galaxy NGC 7469, where long-slit spectroscopy has been performed in the J, H and K bands at the VLT diffraction limit. A preliminary evaluation of the dynamical structure as well as of the gas excitation and the stellar IMF in the starburst, will be proposed based on several lines : Br gamma, H2 lines, CO bands of evolved stars, FeII line of supernovae.

IAU00342 ON THE MULTIPLICITY OF NEARBY CLASS I/FLAT-SPECTRUM SYSTEMS
Presenter: Karl E Haisch
For the past two years, we have been conducting a high resolution near-to-mid-infrared multiplicity survey of Class I and flat-spectrum young stellar objects (YSOs) in six nearby (d < 320 pc) dark clouds. The aim of our survey is to study the binary fractions and separations of Class I/flat-spectrum YSOs and diagnose the luminosities and evolutionary states of their components. Recent sub-arcsecond surveys of young stars have almost exclusively focused on pre-main-sequence T Tauri stars and have virtually ignored younger, Class I and flat-spectrum systems. Thus, we know very little about the multiplicity of self-embedded young stars. In this contribution, we present the results of our high resolution multiplicity survey.

IAU02029 AN XMM-NEWTON OBSERVATION OF THE HERBIG BE STAR, TY CRA
Presenter: Kenji Hamaguchi
We present an XMM-Newton observation of the intermediate mass pre-main-sequence star (Herbig Be star), TY CrA. Strong X-ray emission (7 x 10-12 ergs/s/cm-2: 0.5-10keV) was detected during a 26 ksec exposure. The flux gradually increased by about 30% in 10 ksec in the middle of the observation. The average flux is around seven times higher than those of earlier ASCA and Chandra observations. The source may be in a high state or in a long decay phase of a giant flare. The spectrum does not show any apparent line feature except for an excess at around 1 keV, which matches iron L line emission at temperature of ~1.25 keV, and a marginal enhancement at around 6.7 keV. The continuum emission can be reproduced with an absorbed 2T thermal (Mekal) model, but the elemental abundance at least of the hard component should be less than 0.1 solar. The hot component therefore can be reproduced with a power law model as well. TY CrA is a non-thermal radio emitter. Another non-thermal radio source Rho-Oph S1 does not show apparent X-ray line emission either. The radio emission mechanism may relate to their X-ray emission.

IAU01515 HIGH RESOLUTION SPECTRA OF CIRCUMSTELLAR DISKS OF A STARS
Presenter: Marc Hempel
IRAS observations have shown that about 20% of all A stars are surrounded by dust. Detailed abundance studies of IRAS sources revealed A stars with narrow absorption features in the Ca II K line which are attributed to the presence of circumstellar gas. This is of particular interest in the framework of the formation of planetary systems. In the case of the prototype with circumstellar material -Beta Pictoris- these narrow absorption features are a well-studied phenomenon. Their variability on short timescales corresponds with the scenario of falling evaporating bodies (FEB) approaching the star. Information on the variability of prominent narrow absorptions in Ca K of other A stars is scarce. Investigation of column densities and spectral variations using high-resolution spectroscopy provides an excellent tool to tackle the question whether these features are of circumstellar or rather interstellar origin. Furthermore, it allows to both investigate the FEB scenario and the dynamics of the circumstellar gas. We present results from a time series of Ca K observations carried out with the ESO 3.6-m telescope equipped with the CES at a resolution of 217000 and report the detection of spectral variation in some stars attributable to infalling gas.

IAU01351 SEARCHING FOR THE ENGINE IN NGC 2264
Presenter: Thomas Henning
NGC 2264 is one of the most interesting regions of nearby massive star formation. It contains the relatively isolated luminous infrared source IRS 1 and a variety of other young stellar objects. Our observations, obtained with the IRAM Plateau de Bure millimetre interferometer and supplemented by HST NICMOS data as well as ground-based near- and mid-infrared data, reveal for the first time the detailed structure of this star-forming region. We find that IRS 1 and its low-mass companions are located in a low-density cavity which is surrounded by the remaining dense cloud core. We detect a deeply embedded very young stellar object close to IRS 1, which powers a highly collimated bipolar outflow. In addition, we find strong evidence for an object with a circumbinary disk associated with two bipolar outflows. All those detection will be placed in a general scheme of massive star formation.

IAU01443 MM-CONTINUUM OBSERVATIONS OF HIGH-MASS PROTO-STELLAR OBJECTS
Presenter: Tracey Hill
We report millimetre continuum observations of more than 300 massive star forming complexes collected during a survey conducted on the SEST telescope, at 1.2mm. These complexes were traced using CH3OH maser and UC HII region positions reported by Walsh et al in a survey conducted in 1998. Methanol masers and UC HII regions are considered tracers of the earliest stages of massive star formation. The observations collected using the SIMBA bolometer array at 1.2mm, together with multi-wavelength data from SCUBA (on the JCMT) at 450 and 850 microns, and the MSX satellite at 8, 12, 14, and 21 microns, allow a derivation of the spectral energy distribution (SED) for each of these complexes. The SED will reveal information pertaining to the earliest stages of massive star formation, as well as core specific data such as temperature, mass and luminosity. Using the Australian Telescope Compact Array (ATCA), it is also possible to resolve the more massive and more luminous complexes into individual cores. Mopra data for each of these cores/complexes will reveal their kinematic distances.

IAU02321 EARLY SCIENCE RESULTS FROM THE SMA - TW HYDRA OBSERVATIONS
Presenter: Naomi Hirano
Using the partially completed SMA (Submillimeter Array) with four or/and five antennas, we have observed several molecular lines in the 230 and 345 GHz bands including CO J=2-1 and J=3-2 from the disks and envelopes surrounding low-mass young stellar objects. Here, we present the observations toward the nearest T Tauri star TW Hydra. Its circumstellar disk has been extensively studied as an archetype of proto-solar nebula. We could successfully obtained the images of both CO J=2-1 and 1.3 mm continuum emission from the disk surrounding TW Hydra. The CO J=2-1 emitting region is barely resolved by the present beam of 7.7" x 4.7", which corresponds to 430 x 260 AU at a distance of 56 pc. The size of the gaseous disk is estimated to be 150 - 300 AU in radius. The CO emission line has a width of only ~ 0.7 km/s without significant line wing or local broadening, while shows a small velocity shift of 0.26 km/s across the disk. This suggests that we are viewing the rotating disk nearly along its polar axis.

IAU00293 HIGH RESOLUTION RADIO OBSERVATIONS OF MASSIVE YSOS
Presenter: Melvin G Hoare
I will present the latest results from high resolution radio observations of the ionized stellar winds from massive young stellar objects obtained with MERLIN and the VLA. These include multi-epoch observations of the wind from S140 IRS 1 that confirm its predominately equatorial nature perpendicular to the large-scale bipolar molecular outflow from that source. This is interpreted as observational evidence for the model developed by Drew and co-workers whereby the surface of an accretion disc is blown away sideways by the strong radiation pressure from the central OB star in these young systems. The possible relationship of this initially equatorial ionized flow to the bipolar molecular flow further out is discussed. Other high-mass YSOs have been clearly demonstrated to have radio jets rather than equatorial flows and are therefore much more like the highly collimated magnetohydrodynamic outflows from low-mass YSOs. Possible scenarios to account for this dichotomy in mass-loss geometry and mechanism are outlined as are observational efforts underway to vastly increase the sample of massive YSOs to enable systematic investigations with new high resolution facilities such as e-MERLIN.

IAU00507 OH MASERS IN THE MASSIVE STAR-FORMING REGION AFGL 2591
Presenter: Busaba Hutawarakorn
High-resolution polarization observations of OH masers in star-forming regions enable us to study the magnetic field on subarcsecond scales. We report new MERLIN polarization observations of the 1665- and 1667-MHz OH masers in the massive young star-forming region AFGL 2591. The implications of the alignment of the magnetic fields with the bipolar outflows will be discussed.

IAU02055 MOLECULAR LINE INVESTIGATION OF THE NGC 3576 COMPLEX
Presenter: Paul A Jones
NGC 3576 (RCW 57), one of the brightest H II regions in the southern galactic plane, is associated with a dense molecular cloud that is actively forming stars. Some of the first 3 mm interferometric results from the Compact Array of the Australia Telescope are HCN and HCO+ observations of this complex. These observations show bipolar structure around the continuum peak, which may be associated with outflow. In addition, Compact Array observations of formaldehyde absorption have been used to trace the dynamics of the complex, and indicate that a cloud-cloud collision may be triggering the massive star formation.

IAU00828 ENVELOPE, OUTFLOW AND DISK IN A DEEPLY EMBEDDED PROTOSTAR
Presenter: Jes K Jorgensen
A millimeter interferometry study of the protostellar system NGC1333-IRAS2 is presented. Continuum observations of the main protostellar envelope are analyzed using a model previously derived on basis of radiative transfer simulations of single-dish SCUBA observations (Jorgensen et al., 2002). It is found that the model reproduces the main features of the interferometry observations of the envelope around the main protostar well, but at the same time revealing the presence of a compact, unresolved continuum source -possibly a circumstellar disk. A number of molecular species including HCN and CS show velocity gradients in the material close to the main protostar, suggesting that the protostar either is a close binary or that its characteristic quadrupolar outflow is the result of a singlewide-angle outflow. Very striking is also the prominent outflow-induced bow shock located about 15000 AU from the central protostar, where molecular line maps show spatial differences clearly reflecting the chemical processes resulting from the shock. Single-dish line observations at the central protostar and shocked region are used to constrain the molecular abundances and reveal the differences between the chemistry in the outflow with large enhancements of molecules like CH3OH, SiO and SO, and that in the quiescent envelope system.

IAU00966 SMALL SCALE STRUCTURES OF THE RHO OPH A CLOUD
Presenter: Takeshi Kamazaki
It is expected that the pre-protostellar cores have information about initial conditions from which star formation begins. Thus, in order to study their spatial and velocity structures, we performed 3 mm dust continuum, C17O line and H13CO+ line observations toward the submillimeter sources in the rho Ophiuchus A region using the Nobeyama Millimeter Array. The dust continuum emissions were resolved into six small cores of 600-1100 AU in size. The masses and densities of the small cores are estimated to be 0.054-0.14 M¤ and (2.0-15) x 107 cm-3, respectively. Comparing their derived masses with the masses of uniform density sphere in virial equilibrium, we found that these small cores appear to be gravitationally bound. The molecular line observations also have revealed that they consists of 10-20 small cores which are not only distributed in spatial domain but also in velocity domain, although no systematic motion of the rho Oph A cloud and the individual small cores has been detected. Comparing the total integrated intensity maps of two molecular lines with the 3 mm dust continuum map, we have found that their distributions are different one another and it would be caused by fractional abundance variations of the observed molecules.

IAU02202 STUDY ON STAR FORMING REGIONS BY USING THE VERA
Presenter: Osamu Kameya
The VERA (VLBI Exploration of Radio Astrometry) is the new VLBI system in Japan, which consists of four 20m-diameter antennas with dual beam receiver system at 22GHz and 43GHz bands. It is dedicated to measure position of water vapor masers and SiO J=1-0 masers referring to distant QSOs with accuracy of an order of 10 microarcsecs by using a special dual beam system for the differential VLBI. We have started test-observation phase from last year. The VERA has ability to measure parallaxes and proper motions of star forming regions in our Galaxy. We will show current status of the VERA test observations, and also show some results and future plans.

IAU01225 TENUOUS DISKS AROUND YOUNG G STARS: TEMPERATURE & CHEMISTRY
Presenter: Inga Kamp
The chemistry of circumstellar disks around young (~10 Myr) solar-type stars is mainly driven by the strong UV radiation field of the central star. Stationary non-flaring disk models are used to derive self-consistently the chemical composition and gas/dust temperatures. Such models and high-resolution observations are needed for a better understanding of the transition phase from gaseous protoplanetary disks to dusty debris disks.

IAU02149 ULTRACOMPACT HII REGIONS WITH LOW-DENSITY EXTENDED HALOS
Presenter: Kee-Tae Kim
We have observed extended emission physically associated with many ultracompact (UC) HII regions. The extended emission consists of one to several compact components and diffuse extended envelope, and the UC HII region usually corresponds to the peak of one among the compact components. Thus almost all the UC HII regions may not be bona-fide ionization-bounded UC HII regions but ultracompact cores of more extended HII regions. We have carried out molecular line observations of the UC HII regions with extended envelopes. The molecular clouds are very clumpy and of irregular morphology. The UC and compact components of HII regions are associated with dense molecular cores, while the diffuse extended envelopes develop in the direction of decreasing molecular gas density. Therefore, the hierarchical structure of HII regions appears likely understood by combining the champagne flow model with the hierarchical clumpy structure of massive star-forming molecular clouds.

IAU01188 LOW MASS STAR FORMATION IN TURBULENT MOLECULAR CLOUD CORES
Presenter: Richard I Klein
An inherent difficulty in developing a comprehensive theory of star formation is the formulation of the initial conditions of molecular cloud cores. Since the observational properties of cores have only been determined to sufficient accuracy recently, only now is it possible to stage a realistic theoretical attack on the problem spanning many orders of magnitude in spatial scale. We have developed a powerful 3D, parallel, adaptive mesh refinement (AMR) self-gravitational radiation-hydrodynamics code to address a number of key issues in low-mass star formation. We first use the code to generate turbulent density and velocity fields in a molecular cloud core and show that these are consistent with observation. With these initial conditions, we follow the gravitational collapse and fragmentation of marginally stable turbulent molecular cloud cores, including a self-consistent treatment of the radiation transfer. We will discuss the role of both radiation and turbulence within the cores in determining the outcome of low-mass star formation. In particular, what determines the fraction of an unstable cloud that will fragment into protostellar objects? What determines the distribution of stellar clustering into binaries and multiple systems?

IAU00474 THE PRIMORDIAL BINARY POPULATION IN OB ASSOCIATIONS
Presenter: Thijs Kouwenhoven
Recent observations have shown that a large fraction of the stars is formed in binary or multiple systems. A good understanding of the primordial binary population is therefore necessary for understanding the star formation process. We define the primordial binary population as the population of binaries which is present just after star formation has ceased, but before dynamical and stellar evolution have significantly altered its characteristics. A combination of recent adaptive optics observations and literature data of a combination of visual, astrometric and spectroscopic binaries will be used to reconstruct the primordial binary population of the nearby OB association Scorpius OB2. Detailed numerical simulations will be used to study the dynamical and stellar evolution of the binary population and to characterize the observational biases. At this symposium we present the first results from adaptive optics observations of 200 members of Sco OB2.

IAU01945 THE DETECTION OF MASSIVE PROTOSTARS BY THE ISO SATELLITE
Presenter: Oliver Krause
We have detected very cold, massive and compact molecular clouds using the ISO satellite. The large mass (M > 1000 M¤) and low dust temperature (T < 15 K) as well as the absence of embedded radio continuum sources make them extremely promising candidates of massive star-forming regions at a very early evolutionary stage. The 170 micron ISOPHOT Serendipity Survey is the largest sky survey in the unexplored FIR beyond the IRAS 100 micron band with sufficient spatial resolution to perform an unbiased search for such cold dust condensations. We performed ground-based follow-up observations of this new ISO sample using large single-dish telescopes and interferometry, resolving the objects in the dust (sub)-mm continuum and ammonia molecular line emission. Thermal-infrared imaging allowed to study embedded protostellar objects at sub-arcsecond resolution. The cold dust and dense gas in the new ISO sample have significantly lower temperatures than the existing samples of massive star-forming regions. In addition, several embedded cold and massive cores without mid-infrared counterparts or warm ammonia emission were found. These objects are suggested to be pre-protocluster cores prior to a hot-molecular core phase and indicate that the ISO sample is close to the initial conditions of massive star formation.

IAU01404 HST/ACS IMAGES OF THE GG TAURI AND HD 163296 DISKS
Presenter: John E Krist
We present V and I band images from the Hubble Space Telescope’s Advanced Camera for Surveys (ACS) of the circumbinary disk around the T Tauri system GG Tau and the circumstellar disk and jet of the Herbig Ae star HD 163296. Both disks are optically thick. Direct imaging of GG Tau with PSF subtraction reveals the circumbinary disk in greater detail than in previous HST observations, due to the higher sensitivity and more stable PSF of ACS. Illumination variations, possibly caused by shadowing by circumstellar dust, are clearly seen within the disk. We also confirm the presence of reflecting material near the secondary component of the binary, as was seen in prior WFPC2 images. There is no evidence for "spokes" seen in ground-based adaptive optics images. Our ACS coronagraphic observations of HD 163296 provide the first multi-colour images of the disk and bipolar jet. The images of GG Tau and HD 163296 were obtained as part of the ACS Science Team's circumstellar disk program.

IAU02564 HST MULTI-EPOCH OBSERVATIONS OF THE XZ TAURI OUTFLOW
Presenter: John E Krist
We present HST/WFPC2 observations of the peculiar Herbig-Haro outflow from the binary T Tauri system XZ Tauri. Images taken at seven epochs spanning seven years reveal a poorly-collimated outflow that suddenly became limb-brightened as it expanded into the surrounding medium. The forward edge has decelerated by about 40% and appears to be flattening. The bubble must have initially expanded due to high internal pressure and later transitioned to a ballistic outflow. Both stars are sources of jets, the interactions of which may have resulted in the bubble. Narrow-band images show rapid changes in the emission line structure as the jets interact with the outflow.

IAU01883 PROSPECTS FOR VERY HIGH CONTRAST IMAGING
Presenter: Anne-Marie Lagrange
Large ground-based telescopes and the improving capabilities for correcting the atmospheric turbulence makes it possible to obtain in the optical and near IR sensitive and very accurate imaging of the circumstellar environments. ESO instrumentation plan includes the study for an instrument dedicated to very high contrast imaging. We discuss here the expected performance of an instrument fully designed for this goal and we present the corresponding astrophysical interests for the formation of stars and planetary systems.

IAU00364 HIGH-RESOLUTION MULTILINE STUDY OF HMSF REGION G268.42-0.85
Presenter: Alexander Lapinov
We report results of detailed multiline mapping of high mass star forming region G268.42-0.85 with SEST-15m and CSO-10.4m in different rotational transitions of CS, C34S, 13CS, HCO+, SO, CO, 13CO and C18O. By using developed by us codes for MEM deconvolution, which increase significantly effective spatial resolution of the observed maps, we revealed rotating disk-like structure elongated perpendicular to bipolar outflow visible in DSS image. From derived maps at high spatial resolution we have found strong decrease of the observed species towards central IR object IRAS9002-4732.

IAU00366 HIGH-RESOLUTION STUDIES OF COLLAPSING DARK CLOUDS
Presenter: Alexander Lapinov
We report results of extensive multiline search and detailed study of collapsing cores in more than 50 dark clouds performed in 1998-2002 with MPIfR-100m, IRAM-30m, OSO-20m and SEST-15m. By using developed by us codes for MEM deconvolution, which increase significantly effective spatial resolution of the observed maps, we have studied small-scale intensity distribution in 10 most representative objects. We have revealed differential cloud rotation in central parts of B217SW, L1512, L1544 and some others. We confirmed strong depletion in most of observed species in dense cores of L1544 and L1498. From high resolution HCN spectra we have found increase of the collapse velocity towards center in B335. It is shown that due to resolved hf structure of self-absorbed HCN lines they are extremely good probe to search for and to study collapsing cores in dark clouds and the measured lines are very similar to predicted by us previously in radiative transfer modelling (Lapinov A.V. 1989 Sv.A. v.33, p.132).

IAU02182 INFALL STUDY IN STARLESS CORES WITH CS(3-2)AND DCO+(2-1)
Presenter: Chang Won Lee
We present the results of CS(3-2) and DCO+(2-1) observations of 93 starless cores. Eighty-four cores were detected in both lines. A significant number of CS(3-2) profiles are found to show asymmetric profiles similar to those seen in CS(2-1), while the DCO(2-1) lines usually show a single Gaussian peak. We find that the distribution of the normalized velocity difference DV of CS(3-2) (w.r.t. N2H+) is very similar to that for CS(2-1).Interestingly, the CS(3-2) line often has higher infall speeds than the CS(2-1) suggesting that the cores may have centrally increasing infall speed, and the CS(3-2) is tracing the denser, inner regions of collapsing cores. Comparing the intensities of CS, DCO+, and N2H+, we find a strong hint that CS molecule ubiquitously depletes out of the gas phase in the cores, while DCO+ does not. However, even though CS may be significantly depleted, the CS(3-2) transition should still trace the denser inner, regions of the cores and so we would expect different DV distributions between CS(2-1) and CS(3-2). Rather the similar DV distributions may indicate that cores are in overall quiet stage, and the infalling event tends to occur in overall process through the cores.

IAU01149 NASA'S FAR-IR/SUBMILLIMETER ROADMAP MISSIONS SAFIR AND SPECS
Presenter: David Leisawitz
The far-IR is rich with information about star, disk and planet formation because protostars emit predominantly in this spectral range, and the radiation can escape from the inherently dusty stellar birth sites. Spectral lines contain particularly valuable information about the cooling, collapse, and chemistry of molecular cloud cores and protostars. However, the interpretation of line intensities and profiles is model-dependent; ultimately, high angular resolution is needed to break model degeneracy and definitively characterize the source. Processes occurring on scales smaller than 10,000 AU (70 arcsec at 140 pc) likely affect the stellar initial mass function and determine the products of cloud collapse. NASA's space science roadmap includes the JWST-scale Single Aperture Far-IR (SAFIR) telescope and the 1 km maximum baseline far-IR interferometer, SPECS (the Submillimeter Probe of the Evolution of Cosmic Structure). I will give the scientific motivation for these missions and for the science/technology pathfinder interferometer SPIRIT (the Space IR Interferometric Telescope), describe mission concepts and telescope measurement capabilities, and compare these capabilities with those of the next-generation IR telescopes and with the complementary JWST and ALMA. At 100 microns, SAFIR, SPIRIT, and SPECS will provide, respectively, 2.5 arcsec, 0.25 arcsec, and 10 milli-arcsec resolution at 100 microns.

IAU01302 THE STELLAR CONTENT METAL-RICH EXTRAGALACTIC STAR CLUSTERS
Presenter: Claus Leitherer
Keck and UKIRT optical and near-IR spectroscopy of dusty, metal-rich starburst clusters was obtained in an attempt to constrain their properties from both stellar absorption line and nebular emission line diagnostics. The host galaxies have luminosities of order 1011 L¤. The high spatial resolution and signal-to-noise allow us to isolate individual clusters and in many cases detect absorption features from massive stars. We determine ages and the IMF and compare the results to those found from indirect nebular diagnostics. Differences are discussed in terms of spatial variations and radiative transfer effects in the ISM.

IAU02140 L1551 IRS5 - CIRCUMBINARY ENVELOPE TO CIRCUMSTELLAR DISKS
Presenter: Jeremy Lim
L1551 IRS5 is a binary protostellar system comprising two low-mass stars. Its dusty surroundings consists of a large-scale circumbinary envelope, a possible circumbinary disk, and circumstellar disks around the individual binary components. Here, we present an ongoing study to image the dust emission of the protobinary system at 7 mm in multiple configurations of the VLA. Our objectives are to study the detailed structure of the individual circumstellar disks at the highest angular resolution currently possible at any wavelength, search for the predicted annular gap between the individual circumstellar disks and the circumbinary disk as well as the predicted matter streams that bridge this gap to feed the circumstellar disks, and better delineate the structure and radial intensity (density) profile of the circumbinary disk and envelope. In this poster, we present observations of the circumstellar disks at an angular resolution of ~20 mas (~3 AU) with VLA in A-array and the Pie Town antenna. We also present observations of the circumbinary dust at an angular resolution of 0.7 asec (~100 AU) with the VLA in C-array.

IAU02069 X-RAYS FROM YOUNG STARS AND EGGS IN THE EAGLE NEBULA (M16)
Presenter: Jeffrey L Linsky
The Chandra X-ray Observatory observed the Eagle Nebula (M16), a young star forming region containing the dark columns of dust and cold molecular gas known as the "Pillars of Creation" or "elephant trunks". We identify more than 1,000 X-ray sources coincident with K-band stars that are pre-main sequence stars ranging in spectral type from O to M. A handful of the hard X-ray sources in the pillars are spatially coincident with deeply embedded young stellar objects seen in JHK images. However none of the X-ray sources are associated with the evaporating gaseous globules (EGGs) first observed by Hester et al. (1996).

IAU02033 THE GRANDEUR OF MASSIVE STAR FORMATION REVEALED WITH ISAAC
Presenter: Hendrik Linz
We present selected results from our ongoing investigation of high-mass star-forming regions which are based on infrared observations with ESO's ISAAC camera at the 8.2-m ANTU VLT telescope. Although these young stellar objects comprise a high degree of complexity, our data enable us to disentangle these crowded regions. By means of broad- and narrow-band imaging between 1-5 micron, we performed a thorough characterisation of the embedded population. From imaging polarimetry, conclusions could be drawn on the spatial distribution of the dust grains and the illuminating sources. Special emphasis was put on the importance of an accurate astrometry which has a major impact on the interpretation of the data. In the case of G9.62+0.19, we clarified the true nature of the infrared emission in the immediate vicinity of an hot molecular core. For GGD27 IRS2, we found thermal emission at 3.8 and 4.7 micron caused by a deeply embedded object that powers a large radio jet and has counterparts in our mid-infrared and VLA 7-mm data. The presented results mark another step on the way to reveal the mechanisms of massive star formation. They demonstrate the value of sensitive infrared imaging with the current generation of IR cameras on 8-m-class telescopes.

IAU01273 SEARCHING FOR YOUNG PLANETS WITH AO: THE VIEW FROM HAWAII
Presenter: Michael C Liu
We are using the infrared adaptive optics (AO) systems on the Keck 10m, Gemini-North 8.1m, and Subaru 8.2m Telescopes to search for very low mass companions to young solar-type stars. As substellar objects are more luminous in their youth, it is possible to directly image young Jupiter-mass objects. In order to find them as companions at separations comparable to our own solar system, the principal challenges are the high angular resolution and large dynamic range needed to identify them next to bright primary stars. We present results from our search and discuss efforts to confirm candidate planetary-mass companions. We also present a comparison of the Keck, Gemini and Subaru systems for finding faint close companions, and time permitting, describe next generation AO instruments which will be even more powerful for imaging young planets.

IAU02592 NEAR IR POLARIMETRY AND MAGNETIC FIELDS IN LOW MASS YSOS
Presenter: Philip W Lucas
UKIRT and Subaru near IR imaging polarimetry of several low mass YSOs in Ophiuchus and Taurus at 0.3-0.4 arcsec resolution is presented. The dataset includes HL Tau. The magnetic field structures are probed by 3-D Monte Carlo modelling, incorporating the effects on the polarisation state of multiple scattering and extinction by non-spherical grains aligned with the magnetic field. The models suggest that there is a wide variety of field structures, ranging from axial to toroidal on scales from tens to hundreds of AU. The physical structures of the envelopes and the near IR extinction law are also described.

IAU01793 FRAGMENTATION OF MOLECULAR CLOUDS AND BINARY STAR FORMATION
Presenter: Masahiro N Machida
Using three-dimensional MHD nested-grid simulations, we study the binary star formation process paying particular attention to the fragmentation of a rotating magnetized molecular cloud. We assume an isothermal rotating and magnetized cylindrical cloud in hydrostatic balance. Non-axisymmetric as well as axisymmetric perturbations are added to the initial state and the subsequent evolutions are studied. The evolution is characterized by three parameters: the amplitude of the non-axisymmetric perturbations, the rotation speed, and the magnetic field strength. As a result, it is found that non-axisymmetry hardly evolves in the early phase, but begins to grow after the gas contracts and forms a thin disk. Disk formation is strongly promoted by the rotation speed and the magnetic field strength. There are two types of fragmentation: fragmentation from a ring and that from a bar. Thin adiabatic cores fragments if a thickness is smaller than 1/4 of the radius. For the fragments to survive, they should be formed in a heavily elongated barred core or a flat round disk. In the models showing fragmentation, outflows from respective fragments are found as well as those driven by the rotating bar or the disk.

IAU02284 PREDICTING DUST DISTRIBUTION IN PROTOPLANETARY DISKS
Presenter: Sarah T Maddison
We present the results of three-dimensional numerical simulations that include the effects of hydrodynamical forces and gas drag upon an evolving dusty gas disk. We briefly describe a new parallel, two phase numerical code based upon the smoothed particle hydrodynamics (SPH) technique in which the gas and dust phases are represented by two distinct types of particles. We use the code to follow the dynamical evolution of a population of grains in a gaseous protoplanetary disk in order to understand the distribution of grains of different sizes within the disk and produce synthetic scattered light images of the disks. Our "grains" range from metre to submillimetre in size and we discuss the implication for planet formation.

IAU02212 AN INTERFEROMETRIC STUDY OF MASSIVE STAR FORMATION IN S76E
Presenter: Rui-Qing Mao
An interferometric study of massive star formation in S76E (Mao R.Q., Zinchinko I., Hirano N., Choi M., Yang J.) We present the results of high angular resolution (~3") observations of the S76E, a massive star forming region, at millimeter wavelengths with the NMA. The continuum maps at 2 and 3 mm reveal a cluster of three sources sitting within a submillimeter core seen in our previous single dish 870 micron continuum map. Separated by about 10", two of the strongest sources are compact and associated with water maser spots, while the third one is weak and slightly extended. The two strongest sources are also coincident with two clumps found in CS(2-1) and (3-2) maps. Strong outflow emission is detected in both CS transitions. Combining with our single dish molecular line and continuum results, we discuss evidence of the cluster formation and evolutionary status of these sources.

IAU00643 STELLAR CONTENT OF THE COMPACT STAR FORMING REGION SMC-N81
Presenter: Fabrice Martins
SMC-N81 belongs to the class of "High Excitation Blobs" (HEB) which are compact regions of star formation in the Magellanic Clouds. High angular resolution observations by HST have recently revealed the individual components of these small regions (diameter ~ 10"). These compact HII regions represent a unique opportunity to study massive stars just after birth, which is crucial to better understand their early main sequence evolution. We show here results of the study of SMC-N81. We first concentrate on the nebular properties. We describe the morphology of the region and give estimates of the absorption, excitation, age and of the amount of ionising photons necessary to reproduce the observed nebular emission. Then, the analysis of STIS spectra of the exciting stars shows that they are O stars sub luminous by ~ 2 magnitudes compared to normal dwarfs. This places them near the ZERO Age Main Sequence, which confirms their youth and put constraints on accretion scenarios of massive star formation. Moreover, the winds of the SMC-N81 stars are weaker than both those of normal SMC O dwarfs and the most recent predictions of hydrodynamical models. This is puzzling and challenges the radiation driven wind theory in its current state.

IAU00551 VLBI OBSERVATIONS OF WATER MASERS NEAR HERBIG AE/BE STARS
Presenter: Kevin B Marvel
We present Very Large Array and Very Long Baseline Array observations of water masers associated with Herbig Ae/Be stars. Objects observed with the VLA included V1318S, V645 Cyg, PV Cep, LK H[alpha]234, BD+40[deg]4124, R Mon and W166. Observations of an evolved star, U Equ, were also obtained and indicate no current maser activity from this source. A dynamically scheduled VLBA observation will be completed in late spring 2003 and we will present the detailed results from this observation at this scientific session. The already concluded VLA observations show that BD+40[deg]4124 was found to have a peak flux (V(lsr)=5km/s) in excess of 100 Jy and to be located at a position of 20:20:30.59, +41:21:26.270 (2000.0) while LKH[alpha]234 was found to have a peak flux in excess of 90 Jy (V(lsr)=-11 km/s) and to be located at a position of 21:43:06.33, +66:06:55.807.This work has been carried out with the generous support of the American Astronomical Society and through the National Science Foundation's support of the National Radio Astronomy Observatory and especially the Very Large Array and Very Long Baseline Array.

IAU02092 RESOLVING MAGNETIC FIELDS WITHIN MOLECULAR OUTFLOWS
Presenter: Brenda C Matthews
Using the James Clerk Maxwell Telescope, we have observed linear polarization of the CO 3-2 line arising from the Goldreich-Kylafis effect at several positions along the most extensive outflow from the NGC 2071 IR core in Orion B. These data, and earlier data of the NGC2024 FIR 5 outflow, reveal significant fractional percentage, indicating the presence of magnetic fields in the outflow as expected from theory. These data can test models of dipolar and quadrupolar outflows from protostars, since they predict different alignments with respect to the outflow axis. The spatial confinement of young outflows makes their detection with sensitive, high-resolution interferometers possible, meaning that the same technique can be used with the Atacama Large Millimeter Array to provide much more detailed information on the magnetic field geometry in outflows than is possible with current instrumentation.

IAU00857 THE FORMATION OF MASSIVE STARS
Presenter: Christopher F McKee
Observations show that massive stars typically form in regions of very high surface density, of order 1 g/cm2, corresponding to a visual extinction of about 200 magnitudes. The pressure and density in these regions are orders of magnitude larger than in typical GMCs. A molecular core that forms a massive star is highly turbulent, in contrast to low-mass cores, in which thermal pressure dominates. The turbulent core model for massive star formation treats the core as a two-component polytropic sphere and predicts that the time required for a massive star to form is typically about 105 yr, which is short enough for the accretion to overcome radiation pressure. The model is consistent with the formation of massive stars in dense star clusters. The same formalism can be applied to the formation of massive primordial stars. The millimeter and far-infrared spectrum predicted by the turbulent core model is compared with observation.

IAU02627 HYPERCOMPACT HIIREGIONS SHOW MASSIVE STARS FORM BY ACCRETION
Presenter: Christopher F McKee
If massive stars form by disk accretion, then bipolar outflows should be generated as happens in low-mass star formation. The high accretion rates of massive stars make the outflow gas density very large near the protostar. This gas confines ionizing radiation from a massive protostar, creating a jet-like hypercompact (r<0.01 pc) HII region with a lifetime approximately equal to the accretion timescale (~105 yr). This is much longer than the sound-crossing time, thus solving the "lifetime problem" of these HII regions. Confinement of ionization allows disk and equatorial accretion to continue up to high stellar masses, overcoming a major difficulty of standard accretion models. We present an analytic description of the density distribution of the outflow, and couple this to a realistic model for the accretion rate and protostellar evolution of massive stars. We then calculate the extent of the HII region and its radio spectrum. A detailed comparison is made with high resolution observations of radio sources, including source "I" in the Orion Hot Core. The spectra and morphologies of several sources are consistent with this model. We conclude there is no observational or theoretical motivation for collisional models of massive star formation in typical Galactic high-mass star-forming regions.

IAU02071 THE STELLAR DENSITY IN HIGH MASS STAR FORMING REGIONS
Presenter: S T Megeath
Recent theoretical work has suggested that massive stars may form through the collisional agglomeration of lower mass stars in the dense centers of young stellar clusters. Densities in excess of 100 million stars per cubic parsec are required for collisions to occur rapidly enough to form massive stars (Bonnel et al. MNRAS 2002, 336, 659). We measure the maximum stellar densities attained in young stellar clusters containing ultracompact HII, hypercompact HII regions, and/or luminous infrared sources using deep K-band imaging on 2, 6 and 8 meter telescopes and using NICMOS on the HST with angular resolutions as high as 0.2 arcseconds. The observed clusters are still deeply embedded in their natal molecular gas, and have not undergone the rapid expansion accompanying gas dispersal. We find the maximum densities are below 500,000 stars per cubic parsecs, two orders of magnitude lower than the density needed for rapid collisions. In addition, the stellar density does not peak near the position of the embedded OB stars. We discuss the influence of extinction on these results, and how upcoming SIRTF observations at 3.6 and 4.5 microns may be able to detect very deeply embedded stars invisible in our ground-based data.

IAU01767 SPH SIMULATIONS ON TRIGGERED STAR FORMATION IN BRC IC 1848
Presenter: Jingqi Miao
SPH simulations have been carried out in the study of three bright-rimmed clouds (SFO 11, SFO 11NE and SFO 11E) associated with the HII region IC1848, in order to explore the possibility of star formation in these cloud structures, trace back the likely past and future evolution of these clouds and explain what we observed in a recent star formation census of SFO BRCs. In our modelling, we include both the effect of an ionising radiation field and self-gravitational collapse, also a larger chemical network, refined chemical and dust properties, the calculation of the molecule lines. The influence of the magnetic field and chaotic motion of the molecular clouds are included as well. Therefore our upgraded model could present relatively complete evolutionary pictures of molecule clouds under the consideration. The results from our simulations exhibit the radial striations for a photoevaporated flow of gas from the clouds surface and shows the signals of star formation within all three clouds cores which have the same physical properties as protostellar core, also some outflows are appearing in one of the structures, which are in good agreement with observational pictures.

IAU02385 TWO-DIMENSIONAL MODELS OF PROTOPLANETARY DISK CHEMISTRY
Presenter: Tom J Millar
We have developed a two-dimensional model of a flared protoplanetary disk incorporating a self-consistent treatment of gas and dust temperature, and a detailed treatment of the gas-phase chemistry as well as the freeze out and desorption of material from dust grains. The results show that, in the inner 10 AU of the disk, the gas-phase abundances are dominated by material evaporated from dust grains. The surface layer of the disk shows many of the characteristics of photon-dominated regions.

IAU02387 THE PHYSICAL AND CHEMICAL STRUCTURE OF HOT MOLECULAR CORES
Presenter: Tom J Millar
We have made self-consistent models of the density and temperature profiles of the gas and dust surrounding embedded luminous objects using a detailed radiative transfer model together with observations of the spectral energy distribution of hot molecular cores. Using theses profiles we have investigated the hot core chemistry which results when grain mantles are evaporated, taking into account the different binding energies of the mantle molecules. We find that the resulting column densities are consistent with most of those observed toward the hot core G34.26+0.15 at a time around 104 years after central luminous star formation. We have also investigated the dependence of the chemical structures on the density profile which suggests an observational possibility of constraining density profiles from determination of the source sizes of line emission from desorbed molecules.

IAU01609 METHANOL MASERS: SIGNPOSTS OF MASSIVE PROTOSTARS
Presenter: Vincent Minier
Methanol masers have now been recognised as a likely exclusive signpost of massive star formation. More interestingly, radio observations toward a large source sample have shown that methanol masers are isolated from traditional signposts of massive star formation such as ultra-compact HII (UCHII) regions. A recent Mopra survey toward the so-called isolated methanol maser sources reveals that they could signpost hot molecular cores that are weakly or non-ionised, i.e. a phase of massive star formation earlier than the UC HII phase. Observations with the newly upgraded ATCA at 3/12 mm have been undertaken toward the best hot core candidates from our Mopra survey. We present our ATCA results for the isolated methanol maser source G318.95-0.17. HCO+, CH3OH, HCN and HC3N lines were detected and imaged. The HCO+ and HCN images reveal a bipolar structure aligned with the methanol maser spot line and the distribution of H2 emission areas. CH3OH emission is well confined in an unresolved core. Our data confirm the presence of a hot molecular core at the position of the methanol maser as well as an HCO+ outflow-like structure. These results suggest that G318.95-0.17 harbours a very young massive stellar object, and perhaps a massive protostar.

IAU02164 HOT CORES IN W49N
Presenter: Ryosuke Miyawaki
The giant molecular cloud associated with W49A is one of most active massive star forming regions. W49N in W49A has active masers and cluster of UCHIIs. We present 1-2" resolution maps made with the Rainbow, which is an array combined the 45-m Telescope into the Nobeyama Millimeter Array, at 3.4mm wavelength in the continuum and SO line toward W49N. SO emission shows very effective feature of high abundance and excitation such as Orion KL "hot core". Distribution of SO hot cores of W49N is also adjacent to UCHIIs. Some of them are coincide with CH3CN (Wilner et al. 2000). These hot cores are heated by embedded or nearby massive stars. Some hot cores are in early stage before massive stars ionize their surroundings. Cluster of massive stars is forming in W49N.

IAU02216 PROPERTIES OF MOLECULAR CLUMPS IN THE TAURUS-AURIGA REGION
Presenter: Atsushi Miyazaki
We report the molecular clouds observation in the 13CO J=1-0 emission line in the Taurus-Auriga region by the SIS 25-beam array receiver system (BEARS) with the 45-m telescope of the Nobeyama Radio Observatory. The observation was performed toward an area of about 1deg x 9deg from a dense south region, which includes TMC-1, to a slightly diffuse north region to understand a difference between an ongoing star forming region and a region with still unformed star. We identified molecular clumps in three regions (north, middle, south) and estimated the clump properties. There are different properties of clouds among three regions. For example, the molecular clumps in the north and south region have a larger velocity width than that in the middle region. There are the correlation in the north and south region between 13CO and HI distributions based on Leiden HI 21cm data. This difference in environment may cause the difference in cloud properties. However, our estimated index values of mass spectrum for all three regions are consistent with the index values of the various regions. The origin of the mass spectrum is probably independent from the mechanisms that differ the properties of the clumps.

IAU01635 IMAGING SURVEY OF DISKS AROUND T TAURI STARS WITH THE NMA
Presenter: Munetake Momose
This paper presents the results of an imaging survey of protoplanetary disks around 13 T Tauri stars in Taurus Molecular Cloud with the Nobeyama Millimeter Array (NMA). The survey was carried out over three winter seasons from 1998 to 2001. Dust continuum emission at 2 millimeter from the disks was imaged with the maximum spatial resolution of one arcsecond, which corresponds to 140 AU. Physical properties of the disks (outer radius, surface density distribution, total mass, temperature distribution, and the beta index of dust opacity) are derived systematically from the combination of image-based model fitting and the analysis of the spectral energy distributions (SEDs). We found tendency of disk expansion with decreasing the H-alpha line luminosity, which is a good indicator of accretion activity. This can be interpreted in terms of the evolution of an accretion disk. The disk properties derived in this study are compared with those of ``primordial solar nebula'' assumed in standard theories of the formation of the solar system, and the possible connection between the diversity found in the physical properties of the disks and that seen in extra-solar planetary systems is discussed.

IAU00113 THERMAL STABILITY IN MOLECULAR CLOUDS BY AMBIPOLAR DIFFUSION
Presenter: Mohsen Nejad-Asghar
Ambipolar diffusion, or ion-neutral friction, has long been thought to be an important energy dissipation mechanism in molecular clouds, thus, we would interested to investigate the effect of it on thermal instability of molecular clouds. For this purpose, in the first step, we turn our attention to the linear perturbation stage as outlined by Field (1965), but we consider basic equations which include ambipolar diffusion. In this way, we obtain a non-dimensional characteristic equation which can reduce to the Field’s characteristic equation in the absence of ambipolar diffusion. With numerical manipulation of this characteristic equation, we conclude that (a) the isobaric instability criterion is the same as the absence of the magnetic field, corresponding to the breaking of the magnetic pressure for the reason of ion-neutral slipping; (b) in the perpendicular to the magnetic field ambipolar diffusion can reduces isentropic instability remarkably, thus, causes to increase thermal stability of molecular clouds; (c) in the direction of the magnetic field, isentropic thermal instability is not changed relative to the absence of the magnetic field. We think that this aspect may be another reason for formation of disk-like clumps of molecular clouds.

IAU00171 MAGNETIC FIELD AND OH MASERS IN TWO STAR-FORMING REGIONS
Presenter: Anna Niezurawska
OH masers emission is one of the great tools which allow the searching for star formation. The OH spots occur at the edges of compact H II regions and are a probe of the very close surroundings of a protostar or a newly born star. We present MERLIN observations of OH masers at 4.7 GHz and 1.6 GHz taken in 1999. These are the first maps of excited 4765 MHz masers in Cep A and W75N. The emission nicely coincide with the 1720 MHz transition which gives an opportunity to establish the local physical conditions in that area using theoretical models. The 1720 MHz line shows a Zeeman splitting and indicate a magnetic field strength of 8 mGs at Cep A. We also present the 1665 MHz and 1667 MHz linear polarized components.

IAU00322 THE EFFECT OF COOLING ON THE FILAMENTARY CLOUDS
Presenter: Nasim Nobari
The aim of this work is to present the behaviour of a molecular cloud in the interstellar medium which is supposed to be in a hydrostatic equilibrium (approximately) in the initial conditions, and then, it's affected with a cooling phenomena. For this purpose, we choose a cooling function which represents, very slow flow of the energy from the system to the outside. Most of researches have been worked on spherical symmetric clouds. Here, we assume that the cloud has a cylindrical symmetry. At the first stage, we write the

IAU02223 [NEII] LINE VELOCITY STRUCTURE OF ULTRACOMPACT HII REGIONS
Presenter: Yoshiko K Okamoto
Newly formed massive stars are embedded in their natal molecular clouds and are observed as ultracompact HII regions. They emit strong ionic lines, such as [NeII] 12.8 micron. Since Ne is ionized by UV photons of E>21.6eV, which is higher than the ionization energy of hydrogen atoms, the line probes the ionized gas near the ionizing stars. This enables to probe gas motion in the vicinity of recently-formed massive stars. High angular and spectral resolution observations of the [NeII] line will thus provide significant information on structures (e.g. disks and outflows) generated through massive star formation. We made [NeII] spectroscopy of ultracompact HII regions using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2m Subaru Telescope in July 2002. Spatial and spectral resolutions were 0.5" and 10000, respectively. Among the targets, G45.12+0.13 shows the largest spatial variation in velocity. The brightest area of G45.12+0.13 has the largest line width in the object. The total velocity deviation amounts to 50km/s (peak to peak value) in the observed area. We report the velocity structure of [NeII] emission of G45.12+0.13and discuss the gas motion near the ionizing star.

IAU02656 MILLIARCSECOND RESOLUTION SPECTROASTROMETRY OF HERBIG STARS
Presenter: Rene Oudmaijer
To date, our knowledge of the formation of the intermediate mass Herbig Ae/Be stars is scarce at best. Whether their formation and circumstellar environments are more similar to the lower mass T Tauri stars or more massive stars is still unknown. To pursue this further, we observed a sample of Herbig Ae/Be and T Tauri stars using spectro-astrometry. This technique is capable of probing objects down to scales of a few milliarcseconds, allowing us to observe the small scale material around these young stars. Here we present our results of a spectro-astrometric survey, centred on H alpha, of a sample of 25 Herbig Ae/Be stars.

IAU02013 XMM-NEWTON OBSERVATION OF RHO-OPH CLOUDS
Presenter: Hideki Ozawa
X-ray observation is an important way to investigate protostars because X-ray can penetrate thick dust envelope surrounding protostars and gives us information about central stars directly. It is generally accepted that enhanced magnetic activity of protostars produces X-ray emitting high temperature plasmas via reconnection events, but the details of the mechanism are not well understood. To study this problem, the rho-Oph dark cloud was observed with the XMM-Newton satellite for 30 ks. The rho-Oph dark cloud is a nearby (140pc) well-known active star forming region. Within the 30' diameter field-of-view of XMM-Newton centered on the molecular core F, we detected more than 100 X-ray sources, most of which are identified with Young Stellar Objects (YSOs). There are 11 Class I infrared protostars in the field-of-view of XMM-Newton and we detected X-ray emission from 8 protostars. Their X-ray spectra show high temperature of 2-4 keV and heavy absorption of 4-5 x 1022 cm-2. We report the results of this observation, focusing on the X-ray properties of very young YSOs and protostars.

IAU00955 TRACKING THE EVOLUTION OF DISKS IN OPHIUCHUS BINARIES
Presenter: Jenny Patience
Extensive surveys of the nearest star-forming regions have documented a high frequency of binary stars, making the influence of companion stars a critical consideration for star and planet formation models. Current evidence suggests that the environments around primary and secondary stars may not be equally likely sites of planet formation. The viability of planet formation in the disks encircling the primary and secondary depends upon factors such as the disk mass and lifetime. To investigate further the circumstellar environments of young multiple systems, we are studying the distribution of the dust around Class I and Class II binaries in the Ophiuchus star-forming region. With the high resolution possible with the OVRO mm interferometer, the disk material around each star can be detected individually. These observations provide a comparison to previous data obtained for binaries with different ages and in different star-forming environments. This work was funded by grant NSF AST-9981546.

IAU00956 A KECK ADAPTIVE OPTICS SURVEY OF THE TRAPEZIUM
Presenter: Jenny Patience
With the Keck adaptive optics system we have conducted a high angular resolution binary survey of the Trapezium. The sample consists of 122 targets within 30 arcseconds of the bright theta 1 A-D sources which serve as the reference guide stars. The resolution provided by Keck adaptive optics is required to resolve many binary systems and allows a direct comparison with the IR surveys of the closest star-forming regions over the separation range associated with the peak of the binary distribution. Based on new and previously known binaries, the companion star fraction of the Trapezium is significantly lower than that of the low stellar density Taurus region and slightly lower than regions of intermediate stellar density. In addition to newly resolved companions, the images reveal new isolated sources faint enough to have brown dwarf or planetary masses if they are Orion members. A number of proplyds are also included in the survey area and several exhibit resolved structure, including a previously undetected edge-on disk. Some of this work was performed under the auspices of the US Department of Energy by the University of California, Lawrence Livermore National Laboratory, under contract W-7405-ENG-48.

IAU02340 TRACERS OF STAR FORMATION - H2O MASERS AND CO EMISSION
Presenter: Alison B Peck
Molecular emission (and absorption) lines at radio wavelengths (e.g. radio recombination, maser and CO lines) are among the best tracers of extragalactic star formation, which is often obscured in the optical and UV domain. Furthermore, high spatial and spectral resolution studies of such lines allow us to determine the true distances, kinematics, and dynamics of star-forming regions. Here we present the details of the first single-dish detection and follow-up interferometric study of strong water maser (“kilomaser”) emission in the starburst galaxy NGC2146 and in IC342. In both cases the emission has been found to be associated with off-nuclear regions of vigorous star formation. The strong time-variability of the maser in IC342 is also discussed. In addition, preliminary Sub-Millimeter Array detections of high excitation CO transitions in such nearby galaxies are presented. Interferometric observations of high-frequency rotational transitions of the CO molecule represent a new frontier in the study of the physical conditions of extragalactic star-forming regions, especially in extreme environments such those of starburst galaxies.

IAU00946 OPTICAL/NIR SELECTED BROWN DWARF CANDIDATES IN OMC2/OMC3
Presenter: Dawn E Peterson
At a distance of 450 pc, OMC2/OMC3 is one of the most active sites of ongoing star formation known. Twenty-one protostellar objects have been detected in this region by sub-millimeter surveys (Chini et al. 1997), suggesting that it may be at the early stages of cluster formation. We present a progress report of a detailed investigation into the young pre-main sequence stars surrounding the protostars. We concentrate on a population of brown dwarfs we have recently discovered through a combined optical and NIR study. Candidate brown dwarfs were identified using optical RIz' photometry taken with the 4-Shooter camera at Mt. Hopkins and JHK photometry obtained with SQIID at KPNO. Follow-up optical spectra were obtained with LRIS on Keck I, the Blue and Red Channel Spectrographs on the MMT and with FAST at Mt. Hopkins. To date, spectra have been obtained for 60 candidate members with at least seven candidates identified as having spectral types later than M6, confirming them as bona fide brown dwarfs. The identified brown dwarfs show colours significantly different than the tabulated values for field late M-type stars. We discuss possible explanations for the anomalous colours, including the presence of circumstellar disks around these sub-stellar mass objects.

IAU01937 LINK BETWEEN THE IMF LOW MASS END AND THE PROPERTIES OF H2
Presenter: Daniel Pfenniger
The fragmentation of cold gas is usually thought to proceed as long as the medium radiates faster that its core heats. Thus ISM cores are among the coldest places, until eventually the cores become opaque and heat toward usual star conditions. Now the central pressure for a given column density is the highest for the low mass fragments. At a critical pressure H2 becomes solid or liquid before the core being optically thick. This has for consequence that for sufficiently low mass collapsing clouds the gravitational collapse is stopped first not by opacity but by the H2 incompressibility transition. The resulting almost isothermal cold structures have an incompressible core of H2 surrounded by an extended gaseous atmosphere. Around 5K their typical masses are Jupiter-like and their size a couple of AU. Such structures resemble much the enigmatic cometary globules ubiquitous in planetary nebulae. Since the described mechanism is general and based on well established physics, we expect the systematic formation of such globules below z=11. Their lifetime is determined essentially by the ambient UV excitation. Thus the decrease of the low mass IMF may be explained by the formation, instead of stars, of low mass mildly bound cold globules.

IAU01227 STAR FORMATION IN THE ROSETTE MOLECULAR CLOUD
Presenter: Randy Phelps
An ideal region within which to explore the role of environment on star formation is the Rosette Molecular Cloud, or RMC. At a distance of 1600 pc, the RMC sits at the edge of an ionization front created by stars within the optically revealed cluster NGC 2244.The cloud has a favourable spatial orientation, perpendicular to our line-of-sight, thus allowing for detailed investigations of star formation within it. In this contribution, recent results on star formation within the RMC, in particular a survey for young stellar outflows, will be presented. These initial results highlight the need for higher resolution and higher sensitivity studies, given the relatively large distance of the RMC.

IAU01700 THE EXTENDED METHANOL MASER EMISSION IN W51
Presenter: Chris J Phillips
The W51 complex of HII regions is a luminous and active region of on-going star formation at a distance of about 7 kpc. The region contains all typical tracers of massive star formation (UCHII regions, ammonia cores, infrared components and OH, H2O & ammonia masers) which have been studied in great detail. Observations of the 6.7-GHz methanol maser transition using the Australia Telescope Compact Array (ATCA) detected maser emission extended over 2 arcminutes towards the G49.5-0.4 region of W51. To improve the absolute and relative positional accuracy of the emission, as well as study the distribution of the methanol emission in detail, the European VLBI Network (EVN) has been used to image the entire 2 arcminute field of view. There is growing evidence that methanol masers trace the earliest stages of massive star formation. A complex region such as W51 gives us a unique opportunity to study many individual sites of star formation at different evolutionary stages. In this talk we will present the EVN results and compare the position of the masers to other molecular tracers and HII regions.

IAU01291 PROPERTIES OF PROTOPLANETARY DISKS
Presenter: Vincent Pietu
Interferometric CO line observations of T Tauri and Herbig Ae stars have clearly demonstrated that many of them are surrounded by large Keplerian disks. Proper parametric modelling allowed to derive quantitative information on physical properties of the outer regions of these disks (temperature, density, turbulence ...). For example, recent observations of different isotopes and transitions of CO gave for the first time an estimate of the vertical temperature gradient in the disk of DM Tau. We followed up this framework and observed several disks surrounding stars from 0.5 to 2.5 M¤ in 13CO (2-1) and 12CO (2-1) with the IRAM array. Understanding the chemistry of these objects is also a key issue to be addressed. We thus recently started a chemical survey of DM Tau with the PdBI. In this poster, we present our last observational results of the PdBI survey performed on few T Tauri and Herbig Ae stars located in Taurus-Auriga.

IAU02586 A GEMINI/HOKUPA`A POLARIMETRIC SEARCH FOR DISKS IN MBM12
Presenter: Daniel Potter
Young stellar members of the MBM-12 association were observed in the near infrared using the Hokupa`a/Gemini North adaptive optics system in series with a Wollaston prism based dual imaging polarimeter. Resolved polarization signatures indicative of circumstellar dust illuminated by a central star were found around 3 of the 7 targets observed. These polarimetry data, sensitive to scattered light from circumstellar dust, are compared with thermally sensitive millimeter observations to estimate physical properties of the dust around the MBM-12 association stars observed. In addition, I present a high resolution polarization map of the recently discovered edge-on disk nearby LkHa 263.

IAU00878 HIGH-RES. POLARIZATION MAPS AND NIR COUNTERPARTS OF UCHIIS
Presenter: Elena Puga
The clustered nature of massive star formation constitutes still one of the big open question related to the complexity of the formation process in this mass range. High-spatial resolution NIR imaging aimed to identify and study the stellar content of UCHIIs proved to be very effective in detecting the faintest and in resolving some of these embedded luminous stars. Yet, NIR imaging observations alone still suffer from limitations imposed by the extinction. Alternative techniques must be used to map and understand the complex physical environment in UCHII regions. High-spatial resolution polarization maps can be used to pinpoint the illuminating star or stars even in highly confused and highly extincted environments (Weintraub et al. 1992; Yao et al. 2000). We present Adaptive Optics-assisted observations of two complex UCHII regions (G61.48+0.09 and G77.96-0.006), obtained at the 3.5m telescope on Calar Alto, that will illustrate the results of this technique and compare with the classic imaging. However, we will also show on the source G5.89-0.39, that complementary high resolution observations are still needed to better understand the physical processes associated with UCHIIs.

IAU01699 A MOLECULAR LINE SURVEY TOWARDS MASSIVE PROTOSTELLAR CORES
Presenter: Cormac R Purcell
We have used the 22m Mopra millimetre wave telescope to identify massive young stellar objects in their hot molecular core phase. A sample of 82 sources associated with galactic methanol masers was chosen with the help of IRAS, SCUBA and SEST images as potential candidates. Here we report our observations of these sources using the 3.26mm transitions of methyl cyanide and the 3.4mm transitions of HCN and HCO+. Methyl cyanide emission is detected in 25 sources, for 10 of which we could derive the rotational temperatures using rotational diagram analysis. HCN and HCO+ were detected in 95% of the sources and exhibit signatures of infalling and expanding envelopes.

IAU01332 YOUNG STELLAR OBJECTS IN NGC 6334
Presenter: Jill Rathborne
NGC 6334 is a young star forming complex with at least seven distinct sites of ongoing star formation located along a central molecular ridge. These sites range in evolutionary stage and have associated with them many tracers of active star formation, including 1-mm peaks, far- and near-IR sources, CO hot spots, molecular outflows, H20, OH and methanol maser emission. We obtained L-band observations across the central molecular ridge, using the SPIREX/Abu system at the Amundsen-Scott South Pole Station. These data, combined with near-IR data from 2MASS, reveal the existence of many sources displaying an L-band excess in (J-H) v (K-L) colour-colour diagrams. An excess of emission in the L-band is indicative of the presence of a circumstellar disk, the detection of which is greatly facilitated by inclusion of the L-band data. Approximately 18 sources are selected as Class I objects, with many more objects likely to also be candidates once optical extinction is accurately determined and removed. The majority of these objects correspond to high-mass stars (A–O type), and represent an ideal list of sources in which to study further (e.g. interferometric mm observations) to gain a better understanding of the nature and role of disks in high-mass star formation.

IAU01063 FUNDAMENTAL PROPERTIES OF T TAURI STARS WITH THE VLTI
Presenter: Andrea Richichi
Long-baseline interferometry is a key tool to measure fundamental properties of young stellar objects such as their radii, temperatures, masses. Such data are of critical importance to verify theoretical predictions and to provide a better understanding of the formation and early evolution of stars such as our Sun. Given the small angular sizes involved, and the typical magnitudes of these objects, the direct determination of these quantities has been almost completely impossible until now. With the coming into operation of new powerful interferometric facilities, this area is about to be investigated more fully in the near future. We will review in particular the status of the ESOVLT Interferometer in Chile, its instrumentation and its scientific possibilities in this important field.

IAU02410 WHAT THE VLTI CAN TELL US ABOUT RU LUPI
Presenter: Andrea Richichi
RU Lup (d~200 pc) is one of the most active classical T Tau stars: the equivalent width of H line in its spectrum sometimes exceeds 200A. It is assumed that its activity is due to the disk accretion, with a mass loss of~2x107 solar masses/year. We have calculated the near IR visibility curves for the accretion disk of the star basing on the standard alpha-disk model (Lamzin et al., A&A 306, 877, 1996). We plan to use interferometric observations to derive disk inclination angle and temperature distribution and compare these data with the model. It would be very interesting to test the statement of Takami et al. (MNRAS 323, 177, 2001), based on their spectro-astrometric data, that there is a hole in the disk with outer radius ~3AU.

IAU01152 HIGH ANGULAR RESOLUTION VLA OBSERVATIONS OF L1551 IRS5
Presenter: Luis F Rodriguez
We have used the Very Large Array with the Pie Town antenna of the Very Long Baseline Array to image for the first time L1551 IRS5 at 3.5 cm with an angular resolution of 0.1". These observations clearly reveal the presence of a binary jet, with each component approximately centered on the 7 mm compact protoplanetary disks previously reported. The characteristics of the radio jets will be discussed. We also analyzed VLA archive data at 2 cm for the period 1983 to 1998 and report the detection of proper motions in the components of the binary radio source in L1551 IRS5. The relative astrometry between the two components reveals orbital proper motions that suggest that the total mass and period of the binary system are approximately 1.2 solar masses and 260 years, respectively.

IAU02625 VLT ADAPTIVE OPTICS IMAGING OF THE BN/KL CLUSTER IN ORION
Presenter: Daniel Rouan
We present totally new VLT-NACO adaptive optics images in L and M bands at a resolution of 0.1 arcsec of the region encompassing the very young cluster nearby BN and IRc2. The unprecedented angular resolution is obtained thanks to the use of the unique NAOS infrared wavefront sensor, with BN as the reference source. Adaptive optics images in the S(1) v=1-0, H2 line are also presented. A detailed sensus of the cluster is done and ambiguities between reflection nebulae and true sources are identified. An identification of the primary source in the IRc2 complex is proposed. The major role of IRc2 as the actual source of most of the fast molecular flows is demonstrated. The complex structure of the interstellar medium at a very small scale is put in evidence and the likely role of turbulence is discussed.

IAU01716 THE BALBUS-HAWLEY INSTABILITY IN PROTOSTELLAR DISCS
Presenter: Raquel Salmeron
The Balbus-Hawley instability is a promising source of angular momentum transport in accretion discs. Its behaviour is significantly modified in low conductivity environments where the flow-freezing approximation breaks down. In these conditions, the contribution of Hall effects is crucial for the realistic analysis of discs dynamics and evolution. We present a linear analysis of the vertical structure and growth of this instability in weakly ionised, stratified, protostellar discs. Our method incorporates the effects of the coupling between ionised and neutral components of the gas, the strength of the magnetic field and the conductivity regime of the fluid, which can be a function of height. Hall effects substantially modify the structure and growth of unstable modes, and perturbations grow faster and are active over a much more extended section of the disc than where ambipolar diffusion dominates. As a result, significant accretion can occur in regions closer to the midplane, despite the weak magnetic coupling, because of the high density of the fluid. This presents an interesting alternative to the commonly held view that accretion is relevant mainly in the surface regions of discs, which have a better coupling, but a much lower fluid density.

IAU02218 MOLECULAR CLOUD PROPERTIES ACROSS THE SAGITTARIUS ARM
Presenter: Tsuyoshi Sawada
We are mapping the Sagittarius arm region (l~38deg) in the 13CO J=1-0 line using the 45-m telescope at Nobeyama Radio Observatory with the SIS 25-BEam Array Receiver System (BEARS). The aim of this study is to investigate relations between the properties of molecular clouds and the dynamics of the gas disk in the Milky Way, with a wide-field and high-resolution observations. We have already mapped a 20' x 30' (50 x 70 pc at 8 kpc) region with a spatial resolution of 15" (0.6 pc). The observed 13CO emission are concentrated on three velocity components, corresponding to the near/far Sgr arm and interarm (terminal velocity). The map shows the following three features: (1) 13CO emission is significant and spread even at the interarm region; (2) the emission around the spiral arm shows filamentary structure and distinct clumps; and (3) the emission around the interarm is diffuse, and spread over our entire map.

IAU02680 RESULTS FROM MID-IR OBSERVATIONS OF GALACTIC HII REGIONS
Presenter: Daniel Schaerer
A detailed analysis of the Galactic HII regions observed spectroscopically with ISO is presented with the main aims to constrain/test the ionizing spectra of massive star, and to determine the origin of the observed excitation sequences. For this purpose we have computed extensive photoionization model grids using a variety of recent state-of-the-art stellar atmosphere models. Particular care has been paid to examining in detail the dependences of the nebular properties on the numerous nebular parameters which are generally unconstrained. Our main conclusions are: Recent non-LTE codes including line blanketing and stellar winds show a reasonable agreement with the observations, although non-negligible differences between their predicted ionizing spectra are found. The inclusion of stellar winds is required to obtain adequate ionizing fluxes. The softening of the ionizing spectra with increasing metallicity predicted by the WMBASIC models is found to be too strong. The importance of the metallicity gradient and its combined effect on stellar atmospheres and nebular composition, the variation of stellar evolution with metallicity, and statistical effects due to the IMF are examined in order to determine the main source of the observed excitation sequence. Finally we also discuss possibilities and difficulties in estimating absolute stellar temperatures from mid-IR lines.

IAU01567 MOLECULAR GAS AND STAR FORMATION IN THE SPIRAL ARMS OF M51
Presenter: Eva Schinnerer
The Whirlpool galaxy M51, one of the closest almost face-on grand-design spiral galaxies, has about 50% of its molecular gas in the spectacular grand-design spiral arms. Besides the large number of Giant Molecular Cloud Associations (GMAs) (up to 16 within one spiral arm), numerous OB star clusters reside in the spiral arms as is obvious in high resolution HST data. We mapped six key molecular line probes at high angular resolution (~ 2") in two distinct regions of the spiral arms using the OVRO mm-interferometer. The line data are used to determine the physical properties of the molecular gas such as density and temperature. Comparison between different sites of active star formation reveals correlations between the molecular gas properties and on-going massive star formation. The high angular and spectral resolution permits us to investigate the kinematics between the GMAs (as well as within the GMAs) and the effects of shear and streaming motion on the stability of the GMAs.

IAU00936 DECIPHERING STAR FORMATION WITH THE BARRED SPIRAL LABORATORY
Presenter: Kartik Sheth
What physical conditions initiate or inhibit star formation? Are the conditions common from one region to the next? To answer these questions, we have studied the star formation activity and the parent molecular gas environment in a number of barred spiral galaxies. Barred spirals are ideal for this study because they offer several unique laboratories with distinctive gas kinematics (nuclei, bars, bar ends, and rings), and varying levels of star formation activity (0.001-10 M¤/year). We present high resolution (1 arcsec) CO maps obtained at the Owens Valley Radio Observatory for these various regions, and compare these to Halpha maps which trace the star formation activity. At the bar ends, we find that the SFR is proportional to the number of GMCs, indicating that cloud/complex formation is most important in this transition region. Along the bars, a varying 12CO/13CO ratio is indicative of diffuse gas. In some bars (e.g., NGC 4303), strong shear inhibits the star formation activity, despite high gas surface densities. We quantify these and other physical conditions in the various laboratories, and discuss what conditions may be common to star formation. This work was made possible by NSF grant-AST9981546 which partially funds the Owens Valley Radio Observatory.

IAU02734 TOWARDS CONSISTENT MODELS OF STARLESS CORES
Presenter: Boris Shustov
The complete theory of the earliest stages of star formation can be developed only on the basis of self-consistent, coupled, dynamical and chemical models for the evolution of protostellar clouds. The models including multidimensional geometry, "full" chemistry and 2D/3D radiation transfer still do not exist. We analyze limitations of the existing approaches and main directions of the model improvements: revision of chemical reaction data bases, reduction of chemical reaction network, reasonable choice of model geometry, radiation transfer. The most important goal of modelling of the real objects is to reveal unambiguous signatures of their evolutionary status. Starless cores are believed to be compact objects at very early stages of star formation. We use our results on 1D self-consistent evolution of starless cores to illustrate problems of modelling and interpretation. Special attention is drawn to the radiation transfer problem. New 2D code URAN(IA) for simulation of radiation transfer in molecular lines was developed. This code was used to analyze spectra of starless cores L1544 and CB17. The deduced parameters of these cores are discussed.

IAU01118 MERLIN AND EVN OBSERVATIONS OF 4765-MHZ MASERS IN MON R2
Presenter: Derck P Smits
Spectacular 4765-MHz excited OH maser activity in Mon R2 was observed at 3 epochs with MERLIN and once with the EVN. The EVN observations and one MERLIN run were made when the total flux had flared to its peak of about 75 Jy. MERLIN observations show that the positions of the spots changed during the course of the flaring episodes, and data sets recorded with all four Stokes parameters provide the only known example of 4765-MHz excited OH maser emission with linear polarization. The EVN experiment used radio telescopes at Jodrell Bank, Medicina, Noto and Hartebeesthoek. Interference fringes are present on all baselines, setting new limits on the size of the maser spots and hence the brightness temperature associated with them. The measured brightness temperatures exceed recent model calculations for these masers.

IAU01321 SURVEY OF STARLESSS CORES IN HCN(1-0) FOR INFALL STUDY
Presenter: Jungjoo Sohn
We report our progressive results for a survey of starless cores in HCN(1-0) transitions at 88 GHz with TRAO 14m radio telescope to study infall motions in the cores. The HCN(1-0) contains 3 hyper-fine transitions which have different optical depths and are so believed to trace different layers of the cores which may be useful to see any infall structures if those exist in the cores with infall motions. So far we have observed 59 sources in HCN, among which 52 sources were detected. Thirty sources are found to show infall asymmetry or blue skewed profile in any components of hyperfine ones. We found that six sources tend to have profiles having higher ratio of blue to red component (B/R) in one hyperfine line with the lowest optical depth while having the lowest B/R ratio in the other hyperfine line with the highest optical depth. This may mean that the six cores have infall structure increasing toward the center of the cores and the three hyperfines of HCN(1-0) actually is tracing different infall region. Mapping observations for the depletion problem of HCN(1-0) and detailed spatial structure of the infall motions are also being made and further detailed reduction is underway.

IAU02590 A HUBBLE SPACE TELESCOPE IMAGING SURVEY OF T TAURI STARS
Presenter: Karl R Stapelfeldt
We report on an extensive deep imaging survey of nearby T Tauri stars using the WFPC2 camera the Hubble Space Telescope. The sample consists of 153 young stars, primarily drawn from five major star-forming clouds at distances between 140-160 pc. The targets were generally observed in R and I band filters. The goals of the study were to image reflection nebulosities tracing circumstellar disks and envelopes, and to image emission nebulosities tracing shocked outflows, Extended nebulosity was detected in 52 sources. In 32 objects, reflected light from circumstellar envelopes was detected; the morphology ranges from symmetric bipolar cavities to irregular structures without obvious interpretation. Jet features were resolved in 15 objects, many for the first time. Most interesting are 10 sources where HST directly detects disks in scattered light. For nearly 100 of the targets observed, however, HST/WFPC2 detects no nebulosity at all: only the stellar point spread function is seen. This includes 15 objects where millimeter interferometers have clearly resolved CO disks larger than 3 arcsec in diameter. Possible explanations for these non-detections are discussed.

IAU02591 DEBRIS DISK IMAGING WITH NASA'S SIRTF OBSERVATORY
Presenter: Karl R Stapelfeldt
NASA's Space Infrared Telescope Facility (SIRTF), now scheduled for an August 2003 launch, will open a new window into the structure and evolution of debris disks. We present an overview of disk imaging science to be conducted by the SIRTF GTO teams. Foremost is a major study of the disks of beta Pictoris, epsilon Eridani, Fomalhaut, and Vega, which will be mapped in all imaging and several spectroscopic modes. This program has three major science objectives: (1) Study of the disk spatial structure from MIPS and IRAC imaging; (2) Study of the dust grain composition using the IRS and MIPS SED mode; and (3) companion searches using IRAC. The images and spectra will be compared with models for disk structure and dust properties. Dynamical features indicative of substellar companions' effects on the disks will be searched for. A "Dirty Dozen" additional but generally more distant IRAS debris disks have a strong potential to be resolved at 70 microns, and will be observed with MIPS and IRS. Results from these studies of resolved disks will lay the foundation for understanding the thousands of additional debris disks that SIRTF will detect photometrically.

IAU00075 RESOLVING A GALACTIC STARBURST CLUSTER WITH ADAPTIVE OPTICS
Presenter: Andrea Stolte
The VLT Adaptive Optics (AO) system NAOS-CONICA has been used to obtain high-resolution H and K images of the massive starburst cluster Arches, located at a distance of 8 kpc from the sun close to the Galactic Center. The Strehl ratio of 20% at K-band wavelengths yields a spatial resolution of 86 milliarcseconds (mas), close to the VLT diffraction limit of 70 mas in K. For the first time, the bright cluster center population has been completely resolved. This influences statistical properties such as the luminosity and mass functions, and the fraction of high- to low-mass stars. The high-resolution AO data are compared to HST/NICMOS data of the same field, and the gain in ground-based high-resolution techniques with 8m-class telescopes in terms of resolution and sensitivity is discussed. From these data, the mass function (MF) of the Arches cluster core is derived, and variations of the MF slope with increasing cluster radius, indicating mass segregation, are discussed. The behaviour of the Arches MF is compared to the starburst cluster NGC 3603, located in the Carina spiral arm far from regions as dense as the Galactic Center.

IAU01510 HIGH-RESOLUTION NEAR-IR OBSERVATIONS OF BRIGHT-RIMMED CLOUDS
Presenter: Koji Sugitani
Bright-rimmed globules/clouds around HII regions are considered to be potential sites for triggered star formation due to UV from OB stars. Particularly, those clouds with IRAS point sources are of deep interest from the point of view of ongoing star formation. Although we had already made shallow, low-resolution near-IR observations of these objects (e.g., Sugitani, Tamura & Ogura 1995), we deeply re-observed some of them by using SIRIUS (Simultaneous-colour Infrared Imager for Unbiased Survey), which is equipped with three HAWAII arrays, on the IRSF 1.4m and UH 2.2m telescopes. So we would like to present these recent results of deeper, higher-resolution near-IR observations.

IAU02019 FIRST RESULTS OF NRO-45M STAR FORMATION PROJECT
Presenter: Kazuyoshi Sunada
We present our recent results of the ongoing NRO-45m Star Formation project. The purpose of this project is to understand the formation and evolution of dense star-forming cores. Using the 25-BEam Array Receiver System (BEARS) of the Nobeyama 45m telescope, we are now carrying out mapping observations of 35 nearby (d <~ 200 pc) molecular clouds, including diffuse clouds, dark clouds, and GMCs. We use the 12CO, 13CO, C18O, and H13CO+ (J=1-0) emission lines to cover a wide range of gas density from 102 cm-3 to 105 cm-3. Until now, we have completed the mapping of 8 clouds, and have identified many tenuous clumps and dense cores in the clouds. In this paper, we will compare the physical properties of the clumps and cores among the different clouds, and will discuss how the mass function of the clumps and cores depends on the cloud environment.

IAU02036 H13CO+ DENSE CORE SURVEY IN THE OPHIUCHUS NORTH REGION
Presenter: Kengo Tachihara
C18O dense cores in the Ophiuchus north region have been surveyed for denser gas condensations of H13CO+ compact cores (n > 105 cm-3). The star formation is not active in the region although it has sufficient amount of molecular gas (Tachihara et al. 200), while very active star formation can be seen in the nearby rho Oph cloud. We identified 21 H13CO+ compact cores embedded in 11 out of the 25 previously identified C18O cores. The H13CO+ detection ratio is comparable to the Taurus cloud complex where star formation is more active. Most of these H13CO+ cores have no associated YSO. Only one of them has a cold spectral IRAS point source, 16544-1604, well associated at the H13CO+ intensity peak, which is commonly seen at the star-forming cores in Taurus. An energetic molecular outflow associated with IRAS 16316-1540 exhibit a cavity-like H13CO+ distribution, which are likely to be the remnant cores being destroyed by the outflow.

IAU02136 SMA EARLY SCIENCE RESULTS - CS(5-4,7-6) IN L1551-IRS5
Presenter: Shigehisa Takakuwa
We have been conducting initial scientific observations of low-mass star forming regions with the Submillimeter Array (SMA). As one of our target objects, we have observed L1551-IRS5 in the CS(5-4,7-6) line. L1551-IRS5 is the brightest low-mass protostellar object in the Taurus molecular cloud complex, and has been extensively studied. The CS line observations have revealed a compact (< 300 AU) envelope associated with the protostar. The size, and the mass (~ 0.0023 solar mass) of the compact envelope are orders of magnitude smaller than those derived from previous millimeter interferometric studies (size ~ 2000 AU, mass ~ 0.1 solar mass). There is a clear velocity gradient in the compact envelope from North-West to South-East perpendicular to the axis of the associated molecular outflow. The kinematical properties traced by the CS(5-4) line is similar to those traced by the CS(7-6) line. Our SMA observations in the CS(7-6, 5-4) lines first revealed the kinematics of a very dense (~ 107 cm-3) and hot (> 40K) portion of the molecular envelope around the low-mass protostar.

IAU00300 A MODEL FOR THE INFRARED SED OF LOCAL BLUE COMPACT GALAXIES
Presenter: Tsutomu T Takeuchi
Blue compact galaxy (BCD) is often claimed to share some important characteristics with primordial galaxies (small size, low metallicity, and active star formation). However, except for a few rare objects, local BCDs generally have a significant amount of old stellar population. Even in low metallicity galaxies like SBS0335-052, dust extinction is important, therefore we must consider the effect of dust in local BCDs. In this study we modelled the spectral energy distribution (SED) of local BCDs in Virgo cluster. These BCDs have old stellar population, and consequently, contribution from dust formation by evolved stars cannot be negligible. Dust produced by evolved stars may have intrinsically a power-law-like broad size distribution. On the contrary, dust grains from supernovae have a discrete size distribution. We took into account the different origins of grains and calculated the dust reprocessing of UV photons in two-zone approximation. Our model not only reproduces the observed SEDs, but also it is consistent with their chemical evolution. The contribution of hidden star formation is negligible in Virgo BCDs, in clear contrast with SBS. Comparison between SSCs in Virgo BCDs and SBS by high angular resolution observations may reveal the trigger for the star formation in galaxies.

IAU01436 S128, AN HII AND STAR FORMING REGION IN THE GALACTIC OUTBACK
Presenter: Mauricio Tapia
Calibrated optical narrow-band imaging supplemented by near-infrared imaging of Sh2-128 and Sh2-128N are presented. This region contains a developed H II region and a neighbouring compact H II region associated with a pair of water maser sources. Midway between these, the core of a CO cloud is located. Sh2-128 is an H II region at whose geometrical center lies its principal ionizing star. Slit spectroscopy was used for obtaining nebular line fluxes, abundances and physical parameters of Sh2-128. The present JHKs images show the presence of several point sources and nebular emission knots with large near-infrared excesses in Sh2-128N. One red knot coincides with the compact H II region and a far-infrared emission peak. Star counts in J and Ks show a small cluster of B-type stars, mainly in associated with Sh2-128N. Except for the youngest objects, the stars in the whole region are moderately obscured. Our results suggest that Sh2-128 and Sh2-128N constitute a single complex formed from the same molecular cloud but with ages around one million and 300000 years, respectively. A new distance of 9.5 kpc is derived which implies a galactocentric distance of 13.5 kpc and z=550.

IAU00818 DETECTION OF YSO'S WITH SINGLE MODE INTERFEROMETERS.
Presenter: Eric Tatulli
Young Stellar Objects are exciting sources to investigate for they may provide new understanding about stellar and planet formation process. From past few years, progress in spatial resolution and sensitivity of ground based-interferometers have made such observations possible, allowing us to start probing close environment of stars up to a few AU. As an example, accretion disks around Herbig Ae/Be stars and active TTs have been recently resolved in the IR with the IOTA and PTI interferometers. And we expect in the very near future to reach even fainter and smaller sources, with soon to come large apertures interferometers, like the VLTI and its three beams recombiner AMBER. We expect however those objects to be barely resolved. In such a case, a extreme precision is required in order to be able to discriminate between different models. We present here a formalism that allows to theoretically estimate precisions that can be achieved with single mode interferometers. Applying this formalism to the AMBER recombiner, we simulate observation of T Tauri stars for different telescopes configurations (2 or 3 apertures). We conclude about detection feasibility in term of model-fitting and we prospect performances of image reconstruction.

IAU00221 WHAT CAN WE LEARN FROM DISK FREQUENCY IN YOUNG CLUSTERS?
Presenter: Paula S Teixeira
The origin and evolution of circumstellar disks is one of the main scientific quests intimately related with planetary formation, since disks are known to be planetary nurseries. A study of statistically significant young stellar populations, in differing evolutionary stages and astrophysical environments, can provide fundamental tests for theories of disk and planet formation. We are presently conducting a systematic broadband infrared wavelength study of ten young clusters of different ages, in order to compare their circumstellar disk frequency. In this talk, we report our results of JHK photometry of two nearby clusters in our sample, L1654 and NGC 2547. Having a considerable age difference (1-5 and 14 Myr, respectively), it is expected that NGC 2547 shows a smaller frequency of disks according to present theories of disk dissipation and planetary formation.

IAU00028 HIGH RESOLUTION STAR FORMATION FROM THE GALAXY TO Z = 6.
Presenter: Rodger I Thompson
NICMOS on HST has studied star formation at high angular resolution from nearby sources such as AFGL 437 and the Cone Nebula to Galaxies as distant as a redshift of 6. In each case it has very high and in most cases the highest angular resolution possible at the distance of the objects studied. This is due to the intrinsic angular resolution of HST and the circumstance that many of the star formation regions do not have appropriate visible objects for adaptive optics operation. The presentation will discuss new observations of highly collimated bipolar outflows in AFGL 437 and the induced star formation in the cone nebula. It will then discuss star formation in nearby galaxies, the Schmidt law, and the implications for distant galaxy observations. Another major theme will be the universality of the star formation intensity distribution function found in observations of the NHDF. Here the high resolution is critical to resolve regions on the order of a square kiloparsec in galaxies from a redshift of 1 to 6. This is possible due to the small change in angular size in most cosmologies from z = 1 to 6. A concluding theme is the unification of these observations.

IAU00981 EVOLUTION OF FRAGMENTS RESULTING FROM GAS LAYERS
Presenter: Michihisa Umekawa
We carried out three-dimensional self-gravitational MHD simulations of interstellar molecular gas layer under external pressure. In previous studies, we have shown that gas layers fragment to some gaseous filaments and clumps by self-gravitational instability, depending on the strength of magnetic fields and external pressure. Here, we quantitatively show the numerical results of high external pressure models, in which initial gas layer fragments to small stable clumps (in no magnetized models) or fragments to filaments parallel to the magnetic field lines (in magnetized models) by incompressible mode of self-gravitational instability. By using the numerically obtained mass spectrum of clumps created by the fragmentation of gas layers and by using the time evolution of the maximum mass of clumps, we discuss how the self-gravitational interaction among fragments influence star formation, and we compare these results with our previous works about low external pressure models.

IAU01697 FRAGMENTATION IN THE RHO OPHIUCHI MOLECULAR CLOUD
Presenter: Tomofumi Umemoto
We present the results of extensive mapping observations of the H13CO+ (J=1-0) emission line using the 25-Beam Array Receiver System (BEARS) of the Nobeyama 45 m telescope toward the central cluster forming region of the rho Ophiuchi molecular cloud. The map of the H13CO+ emission shows more compact and clumpy structures like dense cores compared with our previous C18O map. Actually, there is a very good agreement between the H13CO+ map and the dust continuum maps of Motte et al. (1998) and Johnstone et al. (2000), suggesting that the H13CO+ emission is a good tracer to probe very high density regions such as pre-stellar cores rather than the C18O emission which is a column density tracer. We identified high density cores from an analysis of the spatial and velocity structures of the H13CO+ emission. We discuss physical properties of the dense cores and a relationship between the mass spectrum of the dense cores and the stellar initial mass function (IMF).

IAU01898 OBSERVING 3-D MAGNETIC FIELD STRUCTURE IN DR21(OH) CORE
Presenter: Thangasamy Velusamy
We present evidence for the cyclotron interaction effect at arcsec scale on the velocity dispersions in the spectra of ion/neutral molecular species in DR21(OH) observed with the OVRO-MMA. It has been suggested that under average interstellar field strengths the cyclotron interaction between the ions and magnetic fields are strong enough to narrow the linewidth and suppress the line wings in the ion spectra compared to neutral species (Houde et al., 2000, ApJ, 536, 857). The cyclotron interaction provides a measure of the angle between the magnetic field direction and the line of sight, and therefore, it is complementary to conventional polarimetry, Zeeman splitting and dust emission. In the OVRO data, currently available, we see some evidence for the cyclotron interaction in the DR21(OH). The ion H13CO+ linewidths are narrower than the neutral H13CN linewidths. We discuss the analysis and interpretation of the differences in the widths and the shapes of the ion/neutral spectra in DR21(OH) core. We use the cyclotron interaction inferred from the ion/neutral spectral lines to derive the 3-D magnetic field structure of DR21(OH) at arcsec scales by combining with the existing Zeeman measurements and dust/CO polarimetry data.

IAU01530 H2O AND CH3OH MASERS IN A DISK AROUND GL2789
Presenter: Maxim A Voronkov
Radio images of maser spots in the infrared source GL2789 have been obtained as a result of the radio interferometric observations of H2O maser at 22 GHz and methanol maser at 6.7 GHz with the VLBI arrays VLBA and EVN. It was shown that the position of the masers coincides with the optical object within 0.2 arcseconds. The maser spots are located along the line North-South, and their position and radial velocity can be described by a model of the Keplerian disk common for both masers with a maximum radius of 40 AU for H2O maser and 800 AU for methanol maser. Both H2O and methanol maser spots have not been resolved, and lower limits of the brightness temperature are 2x1013 K and 1.4x109 K, respectively.

IAU01464 THE STRUCTURE OF CIRCUMSTELLAR DISKS AROUND BROWN DWARFS
Presenter: Christina H Walker
We present synthetic spectra for circumstellar disks that are heated by radiation from a central brown dwarf. In order to reproduce observed near-IR excess emission from candidate brown dwarfs in the Chameleon, IC348, rho Ophiuchus, Taurus and Trapezium clusters, we require circumstellar disks with large scaleheights. Our models suggest disk scaleheights for brown dwarfs in excess of three times those derived for T Tauri disks. The larger scaleheights in brown dwarf disks are naturally explained by hydrostatic structure models of a passively heated disk around a very low mass star. If the near-IR excess emission observed from brown dwarfs is indeed due to circumstellar disks, then the large scaleheights we find will have a significant impact on the optical and near-IR detectability of such systems. Our radiation transfer calculations show that such highly flared disks around brown dwarfs will result in a large fraction of obscured sources due to extinction of direct starlight by the disk over a wide range of sightlines. We show that the obscured fraction for brown dwarfs may be as high as 70% depending on disk mass and size. This compares with less than 20% for a typical classical T Tauri star.

IAU02004 A HIGH-RESOLUTION STUDY OF STAR-FORMING CLUMPS IN NGC 1333
Presenter: Andrew J Walsh
We have carried out BIMA + FCRAO observations of the busy star forming cloud NGC 1333. Our observations are high spatial and spectral resolution, as well as covering a large area on the sky. This is needed in order to investigate clustered star formation as a whole. We report on N2H+(1-0) and HCO+(1-0), as well as mm-continuum observations toward this region, which allow us to probe not only the quiescent gas (N2H+ and continuum), but also the outflowing gas and the effects of depletion (HCO+).

IAU01910 OVRO OBSERVATIONS OF MOLECULAR GAS IN DWARF GALAXIES
Presenter: Fabian Walter
I will summarize the highlights of our dwarf galaxy survey which we recently completed at the Caltech OVRO millimeter interferometer. The aim of this key-project has been two-fold: (1) map the molecular content of metal-poor systems at high angular resolution and (2) derive the 'infamous' H2-to-CO conversion factor as a function of metallicity. In particular I will concentrate on the Local Group Dwarf Galaxy IC10 where we have obtained a high-resolution (2", 10pc) mosaic of the entire galaxy. Strikingly, our intensive mapping campaign has recovered the presence of vast amounts of molecular gas in the very outskirts - far away from the central star forming regions. This implies that stars can form at large galactocentric radii in dwarf galaxies. The high resolution study of this and other dwarf galaxies (NGC 4214, NGC 3077, IC 2574 and NGC 6822) enables us for the first time to accurately derive the conversion factor of the molecular gas as a function of metallicity: quite surprisingly, the CO-to-H2 conversion factor is found to be similar to the Galactic factor for the lower-metallicity systems of our sample.

IAU00398 A POSSIBLE TRIPLE MASSIVE PROTOSTELLAR SYSTEM
Presenter: Jun-jie Wang
The observational evidence strongly suggests that many protostars are forming in multiple-star systems. In the earliest phase of star formation both low-mass and high-mass protostars will experience the accretion process, and jets/outflows of gas always go along the rotation axes of accretion disks. Thus jets/outflows are good tracers for the deeply embedded protostars, especially for multiple protostellar systems which are interacting with each other. Based on the molecular line observations and near infrared imaging observations on JHK broad bands and H2 S(1) 1-0, FeII narrow bands, we found a candidate of a triple massive protostellar system with at least two possible massive components. Further sub-mm observations with high spatial resolution need to be made so as to provide with more evidence to confirm this discovery.

IAU02038 THE AGE OF SVS 13: ENVELOPE INFALL MODELS
Presenter: Zodiac T Webster
BIMA Interferometer observations of dust continuum emission at 1.3 mm probe protostellar disk and envelope structures of the two brightest millimeter sources near SVS13, from 0.3” to 20”. High-resolution wide-field imaging techniques permit the testing of envelope infall models. Using high resolution interferometer data in conjunction with a previously published single dish map at 1.3 mm (Chini et al 1997) provides both the necessary resolution (0.3”) and large scale sensitivity to distinguish the disks from the envelopes. Combining the interferometer data with the single dish map ensures all the envelope emission is traced. Probing protostellar envelopes at 1.5” resolution permits tracing of the envelope structure on scales from 450 AU to 2500 AU which are unresolved in single-dish maps. Comparisons of the measured envelope profiles at 1.5” resolution to the canonical inside-out collapse model (Shu 1977) delineate the boundary between the collapse and pre-collapse material. Using the local sound speed and the collapse radius permits estimates of the collapse wave expansion time-scale, and thus the age of the protostars and confirm the extreme youth (few x 104 years) of the protostars in this nearby group.

IAU01622 LMC COMPLEX N159: A DIFFERENT STAR-FORMATION ENVIRONMENT
Presenter: John B Whiteoak
The Magellanic Clouds provide a unique opportunity to study molecular clouds in an interstellar environment differing drastically from that in our Galaxy. Accordingly, we have extensively studied the prominent LMC cloud complex containing the H(alpha)-emission region N159, radio continuum emission (designated as MC77 and MRC0540-697A), infrared, X-ray and H2O maser emission, and dense molecular clouds. Here we discuss radio astronomy observations that we obtained during recent years using the Australia Telescope Compact Array and the Swedish-ESO Submillimetre Telescope. Our cm-continuum results show small HII cores superimposed on fainter emission. One prominent core is not visible at optical wavelengths. An extended molecular cloud is densest towards this region, where the cloud shows velocity structure suggestive of cloud-cloud interaction. Some of the molecular abundance ratios differ from Galactic ratios, and are consistent with higher ionisation fluxes. 1-mm dust emission, detected towards the major HII components, also peaks towards this component. H2O maser emission, offset from the main continuum distribution, is near a small emission nebula (N159H) containing an embedded B0V star. It may pinpoint a region in which star formation is on-going

IAU01287 THE MINIMUM MASS FOR STAR FORMATION
Presenter: Anthony Whitworth
Star formation in molecular clouds probably does not involve hierarchical fragmentation, but rather the fragmentation of shock compressed layers formed where turbulent elements collide supersonically. The thermodynamics of opacity limited fragmentation in this situation are quite different (from hierarchical fragmentation) and the minimum mass for star formation may be reduced well below 0.005 M¤. This has consequences for the resolution requirements of numerical calculations.

IAU02608 MODELS OF ISOLATED AND EMBEDDED PRESTELLAR CORES
Presenter: Anthony P Whitworth
We will present radiative transfer calculations of non-embedded and embedded prestellar cores, performed using our accurate Monte Carlo code. Our results for embedded cores indicate that the temperature profiles inside these cores are less steep than those in non-embedded cores. Deeply embedded cores (ambient cloud with visual extinction larger than 15-25) are almost isothermal at around 7-8K. The temperature inside cores surrounded by even an ambient cloud of moderate thickness (AV~ 5) is less than 12 K, which is lower than previous studies have assumed. Our study shows that the best wavelength range to observe embedded prestellar cores is 400-500 micron, where the core is quite distinct from the background. We also predict that very sensitive observations at 170-200 micron can be used to estimate how deeply a core is embedded in its parent molecular cloud. The upcoming HERSCHEL mission (ESA, 2007) will, in principle, be able to detect these features and test our models. Finally, we will present preliminary results from our ongoing study of asymmetric models of prestellar cores (asymmetric cores, asymmetric ambient cloud and/or anisotropic external radiation field), and applications to cores and condensations in embedded protoclusters like rho Oph.

IAU02217 CO(J=3-2) OBSERVATIONS TOWARD THE CARINA NEBULA WITH ASTE
Presenter: Nobuyuki Yamaguchi
We report the first 12CO (J=3-2) observations toward the Carina nebula obtained with the ASTE telescope. ASTE (Atacama Submillimeter Telescope Experiment) is a project to make submillimeter astronomical observations with a new 10-m submillimeter telescope installed at Pampa la Bola (altitude 4,800 m), Chile. The Carina nebula is one of the most active regions in our galaxy. Some evidences of ongoing massive star formation have been reported recently in this region. We found some CO clouds probably interacting with ionized fronts in the 12CO (J=3-2) map. A FIR source is situated near a CO peak in the interacting cloud. It suggests that the triggered star formation occurred in this region.

IAU02204 PROTOPLANETARY DISK FORMATION IN PROTOSTELLAR ENVELOPE
Presenter: Sozo Yokogawa
Aperture synthesis observations of 13CO(J=2-1) emission toward the protostar binary L1551 IRS 5, made with the Nobeyama Millimeter Array (NMA), are presented. The observations with a spatial resolution of 2"-3" have revealed a disklike structure in the central part of the infalling envelope. A distinct velocity gradient is detected along the major axis of the disklike structure, whereas no prominent gradient is detected along the minor axis, suggesting the disklike structure is practically rotating. The velocity gradient along the major axis agrees with the Keplerian rotation around the enclosed mass of 0.6 +/- 0.2 M¤ and the rotational radius is estimated to be 490 +/- 50 AU. The radius is, however, significantly larger than the centrifugal radius of 30 - 300 AU which deduced from the local specific angular momentum of the infalling envelope. We will discuss the inconsistency of both the disk radii, and suggest some hypotheses of a disk formation process in the infalling envelope.

IAU00070 STUDY OF EXTRAGALACTIC STAR FORMATION AT ANGULAR RESOLUTION
Presenter: Zhi-yao Yu
Extragalactic star formation at high angular resolution has been studied. We firstly observe continuum radiation at 18cm in a region surrounding the center of IRAS10173+0828 using the 7 telescopes of MERLIN of the University of Manchester on behalf of PPARC, including the LOVEL antenna. The far-infrared luminosity of IRAS10173+0828 is 4.88 x 1010 L¤. From our contour-map of continuum radiation we have obtained the surface area of 2.91x104 pc2, furthermore the surface density of far-infrared luminosity of 1.68 x 107 L¤ pc-2, S(FIR). Meantime the S(FIR) provides a good measure of the star formation rate per unit area, S(SFR). We also obtain S(SFR) is a higher value of 1.68 x 107 L¤ pc-2. We also obtain the higher ratio of S(FIR)/S MH2, which provides a measure of star formation efficiency. This higher star formation efficiency leads to the production of more heating photons per dust grain, resulting in the high dust temperature. Finally we obtain the higher molecular-to-atomic mass ratio of hydrogen, M(H2)/M(HI). This means a higher efficiency of molecular cloud formation in the region surrounding the center of IRAS10173+0828 (Mirabel and Sanders, 1987, ApJ,322,688; Taniguchi and Ohyama,1998,ApJ,509,L89). This implies that this star formation favours the efficient cloud-cloud collision scenario, which is driven by the violent gas motion in their central regions.

IAU02547 14-M TELESCOPE OF PMO AND RECENT RESULTS ON STAR FORMATION
Presenter: Yingxi Zuo
The 14-m telescope is located 3200 meters high above the sea level at Delingha, Qinghai, China. With a superconducting SIS receiver, the telescope is operating in the millimeter-wave band ranging from 85 to 115 GHz. It was upgraded last year with a so-called multi-spectral-line backends system. With this system the user can obtain three CO lines around 110 GHz simultaneously. In recent years, scientific activities with this telescope have been focused on molecular clouds and star formation researches, such as survey of molecular lines from IRAS sources, large map of molecular clouds, study of molecular clouds and star formation regions, and study of molecular lines of circumstellar envelope. Recent results are covered in the paper.

Missing Abstracts

Last update 22/07/03
The organisers apologise for missing the following abstracts out of the printed Symposium program.

Structure of Cold Cores (Short Review, Session 2, Tuesday 22nd, 11:50am)
Derek Ward-Thompson
Cardiff University
Cold molecular cloud cores are important as the sites of star formation. Starless cores are molecular cloud cores that do not contain any sign of protostellar activity, such as infrared sources or bipolar outflows. Pre-stellar cores are the most centrally condensed starless cores and are believed to represent the stage of star formation that precedes the formation of a protostar. Consequently, they represent the initial conditions of star formation. Furthermore, recent evidence appears to show that the stellar IMF is actually determined at the pre-stellar core stage. If that is the case, then we need to understand the physics of these cores. The physical parameters of the cores, such as density and temperature, are discussed. The detailed structure of bright cores can be mapped. Radial flux density profiles typically show flattened inner regions and sharp boundaries. These have recently been compared to Bonnor-Ebert (B-E) spheres. Hence it has been deduced that the cores are in approximate equilibrium. However, two recent papers have questioned this interpretation. One shows the results of modelling highly turbulent non-equilibrium cores and showing that they can appear to emulate B-E spheres. The other takes data of one core and shows that the radial profile is consistent with several different forms of profile including Plummer spheres, power-laws and B-E profiles. This seems to indicate that radial profiles alone do not uniquely define core structure. A combination of polarimetry data and turbulent MHD modelling indicate that both magnetic fields and turbulence are important in the evolution of cores. Other recent data suggest that cores collapse to form protostars only after turbulence has dissipated, but that they do not collapse from the inside out.
Kirk Jason, Andre Philippe

- Henrik Beuther’s affiliation (Session 6 talk “Interferometry of MSF cores”) is the “Center for Astrophysics, USA”.

- Geoff Blake (Division of Geological & Planetary Sciences, Caltech) will be giving Michiel Hogerheijde’s talk “The transition from collapsing envelope to rotating disk” (Session 11, Friday 25 July, 9:00am) for him.

1046 THE EXTRA FINE STRUCTURE OF THE STAR FORMATION REGIONS IN THE ORION KL.
Presenter: Matveyenko L.I.
We studied a structures of the active star formation regions in the Orion KL in the H2O maser emission. An angular resolution was equal 0.1 mas, that corresponds 0.05 AU. We discovered a super fine structures: a thin accretion disk, an ejector, bipolar outflow, bullets, and envelope, which correspond to the earliest stage of the low mass star formation. The envelope amplified maser emission by about three orders of magnitude at velocity 7.65 km/s that determined the H2O super maser emission. The ejector is a compact bright source < 0.05 AU, Tb > 1017 K. The thin (<0.05 AU) bipolar outflow is highly-collimated (~ 40) stream of matter, include H2O molecules. The velocity of stream is around 10 km/s and bullets 30 km/s. The bullets have comet structure: head - tail. The precession leads to a conical helix streams. Precession period is about 10 yrs.

IAU1728 THE RESISTIVE MAGNETOHYDROCYNAMICS OF PROTOPLANETARY JETS
Presenter: Ko Chung-Ming
We have studied the mass outflow phenomena from the protoplanetary disk by undertaking magneto-hydrodynamical calculations. Sano et al (2000) derived the distribution of magneto diffusivity by taking into account the spatial distribution of many kinds of charged particles in protoplanetary disks and they showed the region where the magneto-rotational instability is stabilized exists between 1AU and 20AU from a central star. We simulated the effect of this region which will affect the mass outflow.

IAU1792 THE MAGNETOSPHERE OF T TAURI SOUTH
Presenter: Guedel Manuel
We report observations of the T Tauri system at 8.4 GHz with a VLBI array comprising the VLBA, VLA and Effelsberg 100m telescopes. We detected a compact source offset approximately ~40mas from the best optical position of the TTau Sb component. The other system components (TTau Sa, TTau N) were not detected in the VLBI data. The compact source is constrained to be less than ~15R¤ in radius. The VLA lightcurve shows rapid variability, which together with circular polarization and its compact nature indicate that the observed flux arises from a magnetically-dominated region. One outburst was observed to have 100% right-hand circular polarization, suggestive of a coherent emission process, most probably an electron cyclotron maser. With this assumption it is possible to estimate the strength of the local magnetic field to be ~1.5-3kG. Using the assumption that the steady gyrosynchrotron emission must have brightness temperature less than 10 billion Kelvin, we argue that this field must be large in size compared to the star.

1098 OVERVIEW OF THE DARWIN MISSION
Presenter Kaltenegger, L.

IAU1775 NEAR INFRARED OBSERVATIONS OF MASSIVE STAR FORMING REGIONS
Presenter Anandarao, Boddapati,

IAU813 NACO: AN EYE-OPENER FOR MASSIVE STAR FORMING REGIONS
Presenter Pasucci, Ilaria

1169 POLARIMETRY OF YSOS IN RHO-OPH
Presenter Beckford Adele

IAU02746 A TIDALLY INTERACTING DISK IN THE YOUNG TRIPLE SYSTEM, WL20
Presenter: Mary Barsony
Combining high angular resolution data from multiple wavelengths has proven to be the crucial factor enabling the discovery of a tidally interacting disk in the WL20 triple system. WL20 is located in the nearby Rho Ophiuchi clouds. Its components have angular separations of 3.17 arcseconds (400AU) in projection E-W, and 2.25 arcseconds (280AU) along a due N-S axis. Sub-arcsecond angular resolution imaging photometry from 1.65 microns to 24.5 microns shows two components exhibiting spectral energy distributions (SEDs) characteristic of T-Tauri stars. However, the third component, WL20S, shows the SED of a self-embedded (Class I) protostar, typically associated with an earlier evolutionary stage than its companions. This age discrepancy is resolved by combining high-resolution millimeter dust continuum maps (obtained with the Owens Valley Radio Observatory's millimeter array) with spatially-resolved near-infrared spectroscopy for each component. The dust continuum images show a warped, disk-like structure centered on WL20S, possibly encompassing WL20W. The near-infrared spectra show two late-type photospheres for the T-Tauri components (K7 for WL20E and M0 for WL20W), with identical values for the continuum veiling (rK=0.2). However, whereas AV=16.3 to the T-Tauri components, WL20S is seen through an additional AV=25 !

UNSW | School of Physics | Department of Astrophysics and Optics | Astronomy in Antarctica
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