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

理解星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。像我们的太阳这样的低质量恒星，通常形成于星星团中。另一方面，质量至少是太阳八倍的大质量恒星非常罕见。高质量恒星的生命短暂，但非常明亮，其特征是强烈的恒星风，有时在超新星爆炸中死亡。研究人员将测试高质量恒星起源于“核心”的模型，其中许多太阳质量的致密气体集中在一个小体积中。 在研究人员的可可项目中，他们用NSF的阿塔卡马大型毫米/亚毫米阵列（阿尔马）观测站调查了这些大质量核心。研究人员将测试预测，即高质量是在非常动荡的冷的高质量核心中诞生的。一个包括观察员和理论家在内的国际合作者小组将支持这项工作。定制的数值模拟将用于详细研究源属性。一些分析工具将转化为简单的高中水平的实验，将通过当地社区中心介绍给学生。 可可项目在ATLASGAL调查的基础上，以870 μ波长覆盖整个银河系内平面，对大质量星星形成的最早阶段进行了系统的搜索。为调查提取的团块是巨大的，密集的，没有高达70 μ波长的红外源。使用敏感的高分辨率阿尔马数据对所有潜在的候选无星高质量块在5千秒差距，可可将揭示是否有任何高质量的核心嵌入这些块。研究人员将提供有关高质量核心的内部密度和温度结构的信息，以及对高质量星星形成早期阶段难以捉摸的寿命的强大约束，其细节程度前所未有。这将涉及对高质量团块的碎裂特性进行详细研究。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星星形成的早期阶段发挥任何作用。总之，这一大规模数据集的综合将对现有的大质量星星形成理论提出严格的限制。该奖项反映了NSF的法定使命，并被认为值得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来支持。

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.