The quest for the origin of the Milky Way's most massive stars

寻找银河系最大质量恒星的起源

• 批准号: 263087346
• 负责人: Dr. Timea Csengeri
• 金额: --
• 依托单位: Max-Planck-Institut für Radioastronomie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/263087346?language=en
• 关键词: quest; origin; Milky; Way; most

Recent results from ground and space-based Galactic scale surveys reveal that the large-scale structure of the interstellar medium is regulated via fast, dynamic processes, strongly supported by numerical simulations as well. Although there is substantial progress made in the past years in our understanding of the ISM and its link to star-formation, the birth of high-mass stars (M>8Msol) is still an enigma in modern astrophysics. Growing observational evidence supports that they form from collapsing super-Jeans cores with ~3000 AU scales with up to 20-40 Msol. These mass reservoirs, which are 10-100x the local thermal Jeans-mass, are associated with flows of dense gas producing shocks also suggesting short formation timescales. Observational evidence lacks, however, of the dominant physical ingredient on small-scales allowing the formation of super-Jeans cores. Furthermore, the currently known most active star-forming sites are typically found to be associated with massive filaments, so called ridges. This project therefore addresses fundamental questions, such as: How important is the role of ridges, large-scale infall and shocks at the onset of high-mass star-formation? Do the most massive stars with 30-120Msol form the same way as the so far observed 15-20 Msol regime? These questions can only be studied now based on large, Galactic-wide samples of potential sites of the next generation of OB-type stars. Playing a key role in the ATLASGAL survey in the past three years, I realized that it provides the best sample of extremely massive young clumps. The objectives of the project are: 1) study the top-heavy fragmentation of massive clumps and reveal if high-mass stars can also form in isolation as suggested by simulations and observations of OB clusters or they necessary from only in clustered environment. I address this by examining the structure of massive clumps from pc to sub-pc scales based on extensive datasets already in hand from state-of-the-art instruments, such as APEX, the IRAM~30m telescope and interferometers, like JVLA, SMA, PdBI. 2) Flows, shocks and cooling seem to be the key to form high-mass stars therefore the importance and impact of dynamic processes need to be better characterized. I plan to exploit spectral surveys to search for kinematic and chemical signatures of flows and shocks in an unprecedentedly large sample of massive clumps. To investigate the small-scale structure of flows and its link to super-Jeans cores I will ask for ALMA observations. Altogether I propose to establish an observational census of the physical and chemical characteristics of the ISM from the scale of collapsing clumps to individual collapsing cores in order to put constrains on formation scenarios. These are the first steps towards a global understanding of how high-mass stars and rich clusters form potentially leading us to understand star-burst events and the origin of super star-clusters.

基于地面和空间的银河量表调查的最新结果表明，星际介质的大规模结构通过快速的动态过程调节，也得到了数值模拟的强烈支持。尽管在过去的几年中，我们对ISM的理解及其与恒星形成的联系取得了重大进展，但高质量恒星（M> 8msol）的诞生仍然是现代天体物理学中的谜。越来越多的观察证据支持它们是由折叠的超吉核与约3000 au尺度的崩溃，最高为20-40 msol。这些质量储层是局部热牛仔裤质量的10-100x，与密集的气体产生冲击的流有关，也表明形成时间尺度很短。然而，观察性证据缺乏小规模的主要物理成分，允许形成超吉核。此外，通常发现当前最活跃的恒星形成位点与大量的细丝有关，即所谓的山脊。因此，该项目解决了基本问题，例如：高质量恒星形成时山脊，大规模进口和冲击的作用有多重要？迄今为止观察到的15-20 MSOL制度的最大恒星是否形成30-120msol的恒星？这些问题只能基于下一代ob型恒星的潜在位点的大​​，银河系的样本进行研究。在过去三年中，我意识到它在Atlasgal的调查中发挥了关键作用，我意识到它提供了最大的年轻团块的最佳样本。该项目的目标是：1）研究大量团块的最重型碎片，并揭示出高质量恒星是否也可以孤立地形成，如模拟和观察到OB簇的建议，或者仅在聚类环境中所必需的。我通过根据最先进的仪器（例如Apex，IRAM 〜30m望远镜和干涉仪）（例如JVLA，SMA，SMA，PDBI）来研究大量团块从PC到子PC量表的结构来解决这一问题。 2）流动，冲击和冷却似乎是形成高质量恒星的关键，因此需要更好地表征动态过程的重要性和影响。我计划利用光谱调查以在空前的大型团块样本中寻找流量和冲击的运动学和化学特征。为了研究流量的小规模结构及其与超级核心的联系，我将要求进行Alma观察。我总之，我建议建立ISM物理和化学特征的观察普查，从崩溃的团块到单个崩溃的核心，以对地层场景构成约束。这些是迈向全球了解高质量恒星和丰富的簇的第一步，这可能导致我们了解星星界的事件以及超级恒星群体的起源。