Title:

The Circumstellar Environment of High-Mass Protostellar Objects




Gary Fuller
Physics Department
University of Manchester Institute of Science & Technology
Manchester, U.K.



Abstract:

     High mass stars shape the physical and chemical properties of
the interstellar medium in a galaxy and can control the ISM's
evolution.  Although relatively few in number, once formed in a
molecular cloud the high mass stars rapidly determine the
cloud's future evolution.  Understanding the formation and early
evolution of massive stars therefore impacts such diverse
astrophysical problems as the birth rate and mass function of
low mass stars, the birth rate of supernovae and pulsars and the
chemical enrichment of galaxies.
     The earliest stages of high mass star formation are much more
poorly understood than the similar stages of low mass star
formation. The answers to many of the questions about high-mass
star formation require observations of their earliest stages of
evolution, before the powerful protostar disrupts its natal
envelope. In this colloquium I will discuss recent results on a
sample of 69 IRAS-selected isolated candidate high mass
protostellar objects (HMPOs). These objects have not yet
developed ultra-compact HII regions and are believed to be in
very early stages of their evolution.
     In addition to discussing results from a submillimetre continuum
imaging survey, I will also discuss the results of a molecular
line survey to probe the velocity field in the circumstellar
regions of these sources.  This survey suggests that the cores
around many of these sources are gravitationally infalling.