The physical & chemical diagnostics of high mass star formation

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Over the past 20 years there have been significant advances in the field of star formation. We have determined that all stars are born deeply embedded and emerge over time as the surrounding material is either accreted or dispersed.  We have also learned that the dynamical and physical evolution during the star formation process is accompanied by a strong chemical evolution.  A large part of our progress in the field of star formation has focused solely on the formation of low-mass stars, predominantly because these objects form isolated from other nearby stars, reducing confusion. However, it has now been recognized that most stars, and especially stars more massive than the Sun, do not form in an isolated fashion. Instead, over approximately 90 per cent of all stars form in clusters, in regions which are also forming massive stars. Similar progress in our understanding of the formation of massive stars has been hampered by several factors: a) The greater distances of the Giant Molecular Clouds that are the birth sites of massive stars makes studies of individual objects difficult. b) Contraction timescales for massive stars are much shorter meaning that examples of the earliest phases are rare. c) The very nature of clustered star formation increases the chances for confusion.  As a result, we still do not understand how massive stars form. In this proposal, funding is requested to tackle some of the most pressing issues in the field of massive star formation. Where are the massive star-forming regions in the Galaxy?  How do they form? What determines the upper end of the stellar initial mass function (IMF)? What are the initial conditions for massive star formation? How do the abundances and evolutions of various chemical species differ from those seen in low-mass star forming regions?