The Formation of Giant Molecular Clouds and their Associations: Confronting Theory with Observations in Spiral Arms

巨型分子云的形成及其关联：理论与螺旋臂中的观测结果的对峙

• 批准号: 203331805
• 负责人: Dr. Eva Schinnerer
• 金额: --
• 依托单位: Max-Planck-Institut für Astronomie (MPIA)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203331805?language=en
• 关键词: Formation; Giant; Molecular; Clouds; their

Galactic spiral arms have long been suspected to govern the formation of Giant Molecular Clouds (GMCs) and subsequent star formation, however, observations and theory remain inconclusive and contradictory. Results from our 40pc resolution molecular gas survey PAWS (PdBI Arcsecond Whirlpool Survey) obtained during the first ISM-SPP funding period show that molecular gas and star formation do not always trace each other, and molecular gas properties and, especially, those of GMCs exhibit a strong dependence on galactic environment (nucleus, arm, inter-arm) -- fully unexpected from current models. This immediately implies that different regimes of GMC and thus star formation exist in spiral disk and that other factors, such as, e.g. dynamical pressure might play an important role. Therefore funding is requested to exploit two new exquisite datasets from ALMA and the Jansky VLA to further investigate the formation of molecular clouds and stars in the presence of spiral arms. Sensitive ALMA observations (5sigma ~ 2e4 M_sun mass limit) of the central 7.5 kpc in the nearby grand-design spiral galaxy NGC628 will be used to investigate the hierarchical structure of the molecular gas and its dependance on galactic environment in unprecedented detail. This investigation is crucial to confirm the unexpected PAWS results. The PAWS M51 molecular gas data will be combined with similar resolution imaging of the thermal radio continuum (regarded a 'gold standard' as star formation rate tracer) to test several theories proposed for star formation 'laws'. The requested post-doc and PhD researcher will work on the first and second project, respectively.

长期以来，人们一直怀疑银河系旋臂控制着巨分子云（GMC）的形成和随后的星星形成，然而，观测和理论仍然没有定论和矛盾。在第一个ISM-SPP资助期内获得的40 pc分辨率分子气体调查PAWS（PdBI弧秒漩涡调查）的结果表明，分子气体和星星的形成并不总是相互跟踪，分子气体的性质，特别是GMC的性质表现出对银河系环境（核，臂，臂间）的强烈依赖-从目前的模型中完全出乎意料。这立即意味着不同的制度的GMC和星星的形成存在于螺旋盘和其他因素，如，例如，动力压力可能发挥重要作用。 因此，需要提供资金，利用来自阿尔马和Jansky VLA的两个新的精密数据集，进一步研究存在旋臂时分子云和恒星的形成。利用阿尔马（ALMA）观测资料（5 sigma ~ 2 e4 M_sun质量极限），对大设计螺旋星系NGC 628的中心7.5 kpc进行了详细的观测，以研究分子气体的等级结构及其对星系环境的依赖性。该调查对于确认非预期PAWS结果至关重要。PAWS M51分子气体数据将与热射电连续谱的类似分辨率成像（被视为星星形成速率示踪剂的“黄金标准”）相结合，以测试为星星形成“定律”提出的几种理论。所要求的博士后和博士研究员将分别从事第一个和第二个项目。