Towards a Global Understanding of High and Low Mass Star Formation

在过去的30年里，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(质量为~1太阳质量或更小的恒星)的形成上，因为这些天体就在附近，被认为是与其他恒星隔离形成的。然而，现在人们认识到，大多数恒星(~90%)是以星团形式形成的，而不是孤立的。此外，赫歇尔空间天文台的观测发现，星际介质中有一个复杂的丝状网。这些细丝分解成致密、紧凑的团块，其中一些形成了从湍流到相干的相变，然后成为恒星的形成地点。这些细丝如何形成、碎裂并随后演化成星团仍然是个未知数。因此，低质量恒星形成的细节并不像人们之前认为的那样被很好地理解。 大质量恒星(质量为8个太阳质量或更高的恒星)的形成更是知之甚少。这些恒星很重要，因为它们是银河系能量生产和重元素丰度的关键驱动力。然而，我们对它们形成的理解受到了一些事实的阻碍：a)它们本质上是稀有的，在它们最早的演化阶段很难找到，所以我们还没有统计上相关的样本；b)我们唯一的大质量恒星形成区域的例子比形成低质量恒星的区域远得多。因此，星团恒星形成的性质使研究单个天体变得困难(因为我们的望远镜有限的空间分辨率将导致独立的天体混合在一起)。 在这项提案中，要求提供资金以解决恒星形成领域(包括低质量和大质量)的一些最紧迫的问题。与新形成的大质量恒星直接相关的性质(从原子气体到引力不稳定的原恒星前核心，再到小的热核心)有什么物理性质？我们还将探索一些关于细丝及其与恒星形成的联系的基本问题；例如：这些细丝如何以及在哪里从反对引力坍塌的湍流支持过渡到纯粹的热支持，并最终转变为恒星形成核心的碎裂？磁场在这一过程中扮演了什么角色？我们还计划开发新的和创新的仪器，帮助我们从观测上解决这些问题。

A large part of our progress in the field of star formation over the past 30 years has focused solely on the formation of low-mass stars (stars with ~1 solar mass or less), because these objects are nearby and were thought to form isolated from other stars. However, it is now recognized that most stars (~ 90%) form in clusters instead of in isolation. Furthermore, observations from the Herschel Space Observatory have identified a complex web of filaments that pervade the Interstellar medium. These filaments break up into dense, compact clumps some of which make a phase transition from turbulence to coherence and then become the formation sites of stars. How these filaments form, fragment, and subsequently evolve into clusters of stars is still uncertain. As a result, it has become clear that the details of low mass star formation are not as well understood as it was previously believed. The formation of massive stars (stars with 8 solar masses or higher) is even less well understood. These stars are important since they are key drivers of energy production and heavy element abundance in the Galaxy. However, our understanding of their formation has been hampered by a number of facts: a) they are intrinsically rare and hard to find in their earliest evolutionary stages and so we do not yet have statistically relevant samples, b) Our only examples of massive star forming regions are much more distant than regions forming low mass stars. Therefore, the nature of clustered star formation makes it difficult to study individual objects (since the limited spatial resolution of our telescopes will cause separate objects to blend together). In this proposal, funding is requested to tackle some of the most pressing issues in the field of star formation (both low and high mass). What are the properties (physical from the atomic gas which must become molecular in form, to gravitationally unstable pre-protostellar cores, to the small hot cores” directly associated with newly formed massive stars. We will also explore some of the fundamental questions that have arisen regarding filaments and their connection to star formation; such as: how and where do these filaments make the transition from turbulent support against gravitational collapse to pure thermal support and, ultimately, to fragmentation into star forming cores? What role do magnetic fields play in the process? We also plan to develop new and innovative instrumentation that will help us to tackle these questions observationally.