Dr Michael Burton (School of Physics, University of New South Wales)

Hot Molecular Cores and the earliest stages of massive starformation - Dr Michael Burton Colloquium

ATNF Marsfield Lecture Theatre

Abstract

This talk will provide an overview of some research programs in the
field of massive star formation conducted within UNSW over the past
few years.

Hot Molecular Cores (HMCs) are regions of warm (T~100K), dense(n~10^7
cm-3) gas, rich in saturated and organic molecules. They have
been found nearby to UCHII regions (ultra-compact HII regions - the
first appearance of ionized bubbles around young stars), a part of
the massive star formation process. However there exist earlier
stages of star formation than the UCHII region phase, and recent
observational evidence suggests that these may be signposted by
methanol maser emission. We report on millimetre observations with
the Mopra telescope of CH3CN (methylcyanide), on mid-IR observations
using the MANIAC camera on the ESO 2.2m telescope, on sub-mm
observations with the SCUBA array on the James Clerk Maxwell
Telescope, and in the mm with SIMBA on the SEST, of isolated methanol
maser sites (ie. away from any other obvious sign of star formation).
Invariably a deeply embedded continuum source is found at or nearby
the maser position. Often there is also evidence of a hot molecular
core, as evidenced through CH3CN mm-lines. We may be witnessing
the very earliest stages of massive star formation, as a warming
protostellar source begins to evaporate organic molecules from the
surface of dust grains, where the molecules were formed. These 'hot
molecular cores' will be prime sites for future observations using
mm-interferometers, and for thermal infrared imaging cameras, in
order to determine the evolutionary stages a collapsing cloud goes
through to produce a star. A current objective is to determine
whether there are chemical signatures which indicate which stage
star formation has reached within a core.