Simon Ellingsen (University of Tasmania)

Masers - Evolutionary clocks for high-mass star formation?- Simon Ellingsen Colloquium

To Be Confirmed

Abstract

Interstellar masers are one of the best, if not the best signpost of
young high-mass star formation regions. They are relatively common,
intense and because they arise at centimetre wavelengths, are not
affected by the high extinction that plagues observations in other
wavelength ranges. Although progress has been slow towards the
important goal of utilizing masers as tools to probe the details of
star formation, the pace of advance has recently accelerated. The
proliferation of complementary high-resolution observations of star
formation regions at millimetre through mid-infrared wavelengths means
that this trend is likely to continue.

The presence of an interstellar maser within a star formation region
signifies ``special'' physical conditions. They are special in the
sense that masing is only predicted to occur for certain ranges of
temperature, density, molecular abundance etc. At present there
remains significant uncertainty about where within star formation
regions the different maser species arise and the evolutionary phase
they are associated with. However, as relatively easily observed
signposts of star formation regions, it would be very desirable to be
able to use the presence or absence of the different maser species as
an evolutionary clock. I will outline recent progress towards the
goal of determining an evolutionary sequence for the common maser
species. Focussing in particular on studies of the mid-infrared
sources associated with the masers, and ATCA observations which are
clarifying our understanding of the relationship between the two
classes of methanol maser.