CoCoA: Cold Cores with the Atacama Large Millimeter/submillimeter Array (ALMA)

了解恒星的形成是天体物理学中最基本的问题之一。宇宙中的大多数恒星形成于密集的星团中。低质量恒星，比如我们的太阳，通常是在星团中形成的。另一方面，质量至少比太阳大8倍的大质量恒星非常罕见。大质量恒星的生命短暂，但非常明亮，其特征是强烈的恒星风，有时会在超新星爆炸中死亡。研究人员将测试大质量恒星起源于“核心”的模型，在“核心”中，许多太阳质量的致密气体集中在一个小体积中。在研究者的CoCoA项目中，他们用美国国家科学基金会的阿塔卡马大型毫米/亚毫米阵列（ALMA）天文台对这些大质量核心进行了调查。研究人员将验证有关高质量物质诞生于非常动荡的冷的高质量核心的预测。一个国际合作团队，包括观察员和理论家，将支持这项工作。将使用定制的数值模拟来详细研究源的特性。一些分析工具将转化为简单的高中水平实验，并通过当地社区中心介绍给学生。研究者试图向少数民族学生介绍科学的过程。CoCoA项目对高质量恒星形成的最早阶段进行了系统的搜索，该搜索建立在覆盖整个银河系内平面的870 μ m波长的ATLASGAL调查基础上。为调查提取的团块是巨大的，密集的，并且没有高达70 μ m波长的红外源。利用敏感的高分辨率ALMA数据对5 kpc内所有潜在的候选无恒星高质量团块进行观测，CoCoA将揭示这些团块中是否存在高质量核心。研究人员将以前所未有的详细程度提供关于高质量核心内部密度和温度结构的信息，以及关于难以捉摸的高质量恒星形成早期阶段寿命的可靠限制。这将包括对高质量团块破碎特性的详细研究。基于alma的一个小样本的尘埃极化数据将告诉我们磁场是否在大质量恒星形成的早期阶段起作用。总之，这个庞大数据集的合成将对现有的大质量恒星形成理论提出严格的限制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding star formation is one of the most fundamental problems in astrophysics. Most of the stars in the Universe form in dense clusters. Low-mass stars, like our own Sun, are much more commonly formed in star clusters. High-mass stars, that are at least eight-times more massive than the Sun, on the other hand, are very rare. High mass stars live a short, but very bright, life characterized by their strong stellar winds, and sometimes a death in supernovae explosions. The investigators will test models that high-mass stars originate in "cores" where many solar masses of dense gas are concentrated into a small volume. In the investigator’s CoCoA project, they surveyed these high-mass cores with NSF’s Atacama Large Millimeter/Submillimeter Array (ALMA) observatory. The investigator will test predictions that high-mass are born in cold high-mass cores that are very turbulent. An international team of collaborators, that includes observers as well as theorists, will support this work. Custom-made numerical simulations will be used to study source properties in detail. Some of the analysis tools will be transformed into simple high-school level experiments that will be introduced to students via a local community center. The investigator seeks to introduce the scientific process to minority students.The CoCoA project has performed a systematic search for the earliest phase of high-mass star formation that builds on the ATLASGAL survey at 870 mu wavelength that covers the entire inner Galactic plane. The clumps extracted for the survey are massive, dense, and devoid of infrared sources up to 70 mu wavelengths. Using sensitive high-resolution ALMA data towards all potential candidate starless high-mass clumps within 5 kpc, CoCoA will reveal if there are any high-mass cores embedded within these clumps. The investigators will deliver information on the internal density and temperature structure of high-mass cores, and robust constraints on the lifetimes of the elusive early phase of high-mass star formation, at an unprecedented level of detail. This will involve detailed studies of the fragmentation properties of the high-mass clumps. The ALMA-based dust polarization data for a small sub-sample will tell us whether magnetic fields play any role in the early phase of high-mass star formation. In summary, the synthesis of this massive dataset will place stringent constraints on the existing theories on high-mass star formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.