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| Mopra
— Millimetre Wave Excellence |
The 22m Mopra telescope near Coonabarabran is currently the
largest single dish mm-wave telescope in the southern hemisphere
and the fourth largest of its kind in the world. Thanks to a
collaborative project between UNSW and CSIRO the facility was
upgraded in 1999 from a 15m diameter millimetre telescope to
a 22m millimetre telescope.
At the present time a number of other Southern Hemisphere
telescopes are being planned and built around the world. The
US National Radio Astronomy Observatory and the European Southern
Observatory are in the last stages of planning ALMA, a large
synthesis sub-mm/mm telescope to be completed in 2011 on the
Atacama Plateau in Chile. Before then Australia has a window
of opportunity as the only country in the southern hemisphere
with a millimetre-capable interferometer – the Australia
Telescope Compact Array. Mopra occupies a unique position,
allowing molecular surveys of large portions of the southern
sky from which interesting astronomical sources may then be
selected for detailed investigation with the Compact Array.
Mopra was used to search for the biologically significant
molecules propylene oxide and glycine in the interstellar
medium. The detection of either of these molecules would be
of great significance for the origin of life question because
of the possible extraterrestrial origin for both primordial
biological molecules and for the chiral imbalance found in
both living systems and in meteorites. The Star Formation
group at UNSW also swept the southern galactic plane for carbon
monoxide, measuring the distance to known medium-mass star
formation regions within 1 kiloparsec of the Sun. The goal
is to correlate protostar properties (mass, density, temperature,
bulk motions) with their luminosity (i.e., mass), covering
the gap usually not addressed in studies of low- and high-mass
star-forming regions.
The telescope has had its fair share of international visitors
also. In collaboration with the University of Leeds, kinematic
distances were measured towards a sample of mid-infrared sources
discovered through the MSX satellite mission. Kinematic distances
are crucial to determining the luminosity of the candidate
protostars and identifying near-by low mass young stellar
objects. This is essential if we are to understand massive
star formation as a function of mass, age, environment and
location. With the Center for Astrophysics in the USA we collaborated
to use Mopra to test the idea that star formation occurs by
coalescence by looking for any relative motions between star-forming
condensations. Such condensations are expected to move with
respect to the ambient material in this scenario, as they
gravitate to the centre of a cluster where they can coalesce
to form more massive stars.
Cormac Purcel
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