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 This page is a little out of date, but I do promise to update it one day!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 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.
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.
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.
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.
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.
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
Trying to preserve the only remaining
extant wetland in Randwick.
Picture Gallery
Further contributions very welcome!
Sketch of
Fine Structure Constant measurements
Spectrum for
Fine Structure Constant measurements
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
