Stars
form deep within dense clouds of gas and dust which absorb light at
most wavelengths. However, these clouds are transparent at radio
wavelengths enabling radio telescopes to probe the star formation
process. Molecular masers (Microwave Amplification by Stimulated
Emission of Radiation) are the radio analogue of lasers and occur
naturally in some astrophysical environments, including near where
high-mass stars are forming. Masers indicate the presence of
specific physical conditions and are potentially very powerful probes
of the star formation environment. However, the processes which
produce masers are complex and cannot easily be determined from a
single observation. Fortunately some molecules exhibit masers
from a number of transitions at different frequencies. Where
these masers are found in the same source models are constrained by the
requirement that they produce emission from each of the transitions in
the observed intensity ratio.
A team consisting of observational astronomers from the University of
Tasmania and the Australia Telescope National Facility and
theoreticians from Monash University and Ural State University have
been successfully using the method described above to improve our
understanding of the early stages of the formation of high-mass stars.
A project funded by the Australian Research Council is underway to
collecting data on a range of methanol and OH masers towards many
sources to better understand the physical conditions during the
evolutionary phase of star formation corresponding to the presence of
these masers. As part of the same project we are also undertaking
detailed modelling of a small number of sources that show maser
emission in a large number of transitions as in these cases we are able
to tightly constrain the maser models.
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Dr
Simon Ellingsen:
Collaborators:
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Intraday Variability
AGN