The physical & chemical diagnostics of high mass star formation

在过去的20年里，在恒星形成领域取得了重大进展。我们已经确定，所有的恒星都是在深嵌的地方诞生的，随着时间的推移，周围的物质要么被吸积，要么被分散。我们还了解到，恒星形成过程中的动力学和物理演化伴随着强烈的化学演化。我们在恒星形成领域取得的很大一部分进展仅仅集中在低质量恒星的形成上，主要是因为这些天体的形成与附近的其他恒星隔绝，减少了混乱。然而，现在已经认识到，大多数恒星，特别是比太阳质量大的恒星，并不是孤立地形成的。相反，大约90%以上的恒星是在星团中形成的，而星团所在的区域也在形成大质量恒星。在我们对大质量恒星形成的理解方面，类似的进展受到几个因素的阻碍：a)作为大质量恒星诞生地点的巨大分子云距离更远，使得对单个物体的研究变得困难。b)大质量恒星的收缩时间尺度要短得多，这意味着最早阶段的例子很少。c)星团形成的本质增加了混淆的可能性。因此，我们仍然不知道大质量恒星是如何形成的。在这项提案中，资金被要求解决大质量恒星形成领域的一些最紧迫的问题。银河系中巨大的恒星形成区在哪里？它们是如何形成的？是什么决定了恒星初始质量函数（IMF）的上限？大质量恒星形成的初始条件是什么？各种化学物质的丰度和进化与在低质量恒星形成区域中看到的有什么不同？

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?