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

了解恒星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都以致密星团的形式存在。像我们的太阳这样的小质量恒星更常见地形成于星团中。另一方面，质量至少比太阳大八倍的大质量恒星则非常罕见。大质量恒星的寿命很短，但非常明亮，以它们强烈的恒星风为特征，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被集中在一个小体积中。在研究人员的可可项目中，他们利用美国国家科学基金会的阿塔卡马大毫米/亚毫米阵列(ALMA)天文台对这些高质量的岩芯进行了观测。研究人员将检验关于高质量物质诞生于非常湍急的冷高质量核中的预测。包括观察员和理论家在内的国际合作者团队将支持这项工作。将使用定制的数值模拟来详细研究震源特性。一些分析工具将被转化为简单的高中水平的实验，将通过当地的社区中心介绍给学生。这位研究人员试图向少数族裔学生介绍这一科学过程。可可项目在覆盖整个银河系内平面的870亩波长的ATLASGAL调查的基础上，对大质量恒星形成的最早阶段进行了系统的搜索。为调查提取的团块质量大、密度高，并且没有高达70亩波长的红外源。使用敏感的高分辨率ALMA数据，对5kpc内所有潜在的无恒星高质量团块，可可将揭示这些团块内是否有任何高质量核心嵌入。研究人员将以前所未有的详细程度提供关于高质量核心的内部密度和温度结构的信息，以及对高质量恒星形成难以捉摸的早期阶段寿命的强有力限制。这将涉及对高质量团块碎裂特性的详细研究。基于ALMA的小样本尘埃极化数据将告诉我们，磁场是否在高质量恒星形成的早期阶段发挥任何作用。总而言之，这一海量数据集的合成将对现有的高质量恒星形成理论施加严格的限制。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.