Michael Burton

BA (hons), MA (Cambridge), PhD (Edinburgh), FASA

Michael Burton Michael Burton with the IRPS at the South Pole

Michael is a lecturer in astronomy and physics in the Department of Astrophysics at UNSW. His research revolves around applying the techniques of observational infrared astronomy to the understanding of our Galaxy. He is also heavily involved with the development of Antarctic astronomy. This page is a little out of date, but I do promise to update it one day!

His research interests and professional responsibilities include:

The Excitation of Molecular Clouds.

This is Michael's principal research activity, and involves studying the excitation of the hydrogen molecule by interstellar shock waves and by UV-fluorescence. Such activity takes place in star forming regions, including photodissocation regions (PDRs), the surfaces of molecular clouds heated by UV radiation. This work involves a broad-ranging observing programme applying a combination of imaging, spectroscopic and polarimetric techniques to study the hot gas in molecular clouds. While it has concentrated on the near-IR spectrum from the v=1 vibrational level of H2, it has developed to study the emission from highly-excited levels of the molecule. Such lines allow us to distinguish between the relative merits of competing models for the emission, which diverge in their predictions for the population of higher energy levels. It involves, for instance, the first measurements of the molecular hydrogen emission in the optical CCD regime. Other aspects of Michael's work include observing the H2 line profiles at high spatial resolution, to probe the structure of bow shocks, and comparing the distribution of different emission lines in a source. An example here includes the spectacular discovery of a plethora of bullets from an explosion in the core of the Orion Nebula. Such imaging has been greatly facilitated by the introduction of UNSWIRF, our group's wide-field near-IR imaging Fabry-Perot. A recent development has been the use of the SPIREX/Abu IR camera at the South Pole to study the photodissociation regions of the NGC 6334 star forming complex through the PAH's 3.28 micron emission band.

The Orion Bullets The Orion Nebula in the near-IR Orion Bullets seen by NICMOS

The Bullets in the near-IR (AAT/IRIS)

Orion Nebula in the near-IR (AAT/IRIS)

The inner Bullets in OMC-1 (HST/NICMOS)

Methanol Masers and Massive Star Formation.

The various stages of the star formation process, from intial collapse of a cloud core, through the formation of a disk and outflow, to the emergence of a young star from its natal cloud, are now beginning to be defined from an observational basis. Massive star formation, in particular, is a spectacular event which can be seen across the Galaxy. Working with my (former!) graduate student Andrew Walsh, on an investiagtion of 6.6GHz methanol maser emission associated with the ultra-compact HII region phase of massive star formation (when an ionized bubble forms around the star), it became apparant that the masers actually predate the UCHII region phase, and may be a signpost to the very earliest stages of the formation process. This work is the subject of Andrew's thesis and is much better described by him. The work has opened up new avenues of investigation into star formation, including searching for (and discovering!) new embedded sources (through mid-IR imaging with MANIAC), and new outflows (through H2 imaging with UNSWIRF), associated with the sites of methanol maser emission. Recently we have concentrated on the newly discovered phenomenom of 'hot molecular cores', which may mark the very beginning of the massive star formation process.

A typical spectrum from the Parkes survey with several masers present

A typical 2 micron image with an UCHII in the centre (ANU 2.3m/CASPIR)

The Galactic Centre.

The hostile environment of the Galactic Centre is an unlikely place to find both molecular clouds and star formation, but it is in fact home to both. Massive star formation is occuring within the central 2 parsecs, and in a number of clusters within the inner 100 parsecs, of our Galaxy. The WN and O-B stars within the nucleus form a population I core to our Galaxy, whose (unobserved) lower mass members may provide the bulk of the mass within the central parsec? Or it may lie in a million solar mass black hole? Michael's work involves, particularly, studying the stellar population in these young clusters, to determine the nature of the massive stars that are forming from their near-IR emission spectrum. A recent development has been imaging the molecular hydrogen emission from the circumnuclear disk and in the Sgr A East supernova remnant to understand its excitation and dynamics. This combines both HST/NICMOS and the AAT/UNSWIRF, the former to provide exquisite spatial resolution, the later to remove the strong continuum emission from the stars and to measure the gas velocities.

Galactic Centre in the near-IR

A near-IR (JHK) image of the Galactic Centre (AAT/IRIS)

The Interaction of Supernova Remnants with Molecular Clouds.

Supernovae must commonly explode within or nearby to their natal molecular clouds. Their expanding blast wave interacts and overuns these clouds. Yet relatively few such examples are known. Such a SNR looks different to `conventional' remnants, with the bulk of the emission irradiated in the IR rather than the optical, through molecular hydrogen and atomic fine-structure lines. These SNRs provide a laboratory to examine the interaction of a shock wave with molecular gas, uncontaminated by the activity associated with star forming regions where such events are usually observed. Michael has been studying these interactions in several Galactic and LMC remnants, undertaking wide-field near-IR imaging of the molecular hydrogen and ionized iron emission, and measuring their total energy budget. The recent suggestion that 1720 MHz OH maser emission may be a signpost to this activity has lead to a new program to search for (and find!), associated shocked molecular hydrogen line emission.

Vela SNR Vela filaments

The Vela SNR seen by the Schmidt Telescope

with some shocked filaments seen by the AAT

Astronomy from the Antarctic Plateau.

The extremely dry, cold and tenuous air above the high Antarctic plateau provides the pre-eminent location on the Earth for the observation of the particle and photon fluxes incident on our planet from space, across much of their energy spectrum. This is particuarly so in the IR and millimetre regimes, where the cold vastly diminishes the IR thermal background, and the dry and stable air significantly improves the atmospheric transmission over mid-latitude sites such as Mauna Kea. Of course there is a tremendous technological and logisitical challenge to be overcome in order to build an observatory in this, the most remote and inhospitable region of our planet, at least from a human perspective. Michael is participating in the CARA/JACARA site testing campaign at the South Pole, and actively involved in the international promotion and development of Antarctic astronomy. This includes the AASTO, or `Automated Astrophysical Site Testing Observatory', and the SPIREX/Abu near-IR camera. Further details can be found on the JACARA home page. For some pictures of Antarctica have a look at the South Pole Picture Gallery.

The AASTO at the South Pole The SPIREX Telescope at the South Pole

The AASTO seen from our South Pole Webcam

The 60-cm SPIREX telescope at the Pole

Millimetre Astronomy.

Millimetre astronomy is about the study of molecules in interstellar space. A rich spectrum of rotational lines emits in the microwave regime, with the fundamental (J=1-0) lines of abundant species such as CO, HCO+ and HCN emiting near 3mm. Each molecular species has a different critical density and thus their observations allows us to probe a wide range of parameter space in molecular clouds, from the overall structure of the clouds, through their collapsing filaments, to the dense cores where new stars are being born. Millimetre astronomy is the key to understanding the overall environment in star forming regions. Even from the relatively moist observing sites in Australia the 3mm portion of the spectrum can be readily observed, and Australia is now developing a mm interferometer for the Australia Telescope Compact Array at Narrabri. Essential for maximising the return from the interferometer is a single dish telescope. UNSW are now upgrading the Mopra antenna at the foot of Siding Spring Observatory to be mm-capable over its full 22-m surface. When this is done Mopra will the the 4th largest mm-telescope in the world and the largest in the Southern Hemisphere. With John Storey I am developing a scientific program to utilise Mopra and exploit this exciting new opportunity. Further information on the Mopra project can be found on the Mopra web pages.

The Mopra Telescope

The Mopra 22-m Radio Telescope

Science Communication.

Communication is an important ability for the professional scientist, not just to one's peers or even the scientific community, but to the public at large. In today's world of economic rationalism it is ever more important to explain both the excitement of leading edge science, and its importance to the development of our society, to a wide audience. I contribute to this in several ways, such as through giving public talks, speaking about astronomy on the radio (here me every second Monday at 5:45pm on ABC radio with James O'Brien) and through the `Australian Science Communinicators'. I am one of the organisers of an exciting new venture, `Science in the Pub' , or SciPub! Come to the Duke of Edinbugh pub in Pyrmont the last Wednesday of every month to hear two prominent scientists debate hot issues in science.

SciPub Logo

Professional Responsibilities.

Bibliography of Published Works

Bibliography as listed with the Astrophysical Data System

Refereed papers, as listed with the Astrophysical Data System (Papers on Cassini or Volcanoes are by another M Burton!)

All papers with query parameters

Refereed papers with query parameters.

 

Postgraduate Research Projects

If your are interested in undertaking postgraduate research with Michael Burton then further information on possible projects that he has available are described here.

Teaching

Conservation

Bundock Wetlands

Picture Gallery

The Y2C!

Sketch of Fine Structure Constant measurements

Spectrum for Fine Structure Constant measurements

Michael Burton

School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.

Tel: +61-2-9385-5618

Fax: +61-2-9385-6060

Email: M.Burton@unsw.edu.au

Last updated: 2009-01-12