The Untimely Deaths of Star Clusters

星团的英年早逝

• 批准号: 2307950
• 负责人: Mordecai-Mark Mac Low
• 金额: $ 54.63万
• 依托单位: American Museum Natural History
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2307950&HistoricalAwards=false
• 关键词: Untimely; Deaths; Star; Clusters

Most stars, including our own Sun, form in clusters of hundreds to millions of stars. As these clusters grow older, they quickly begin to lose stars. This happens both from stars pulling on each other with gravity, and from the gravity of nearby massive gas clouds. These stars spread out from the cluster but still move with a similar velocity. Such groups of stars moving together are observed in the neighborhood of the Sun. The stars heat the gas with ultraviolet radiation, winds, and supernova explosions. The investigators will study how clusters form and disperse, using computer simulations. The proposed work has three goals: 1) to predict the kind of cluster that will form from a given gas cloud; 2) to test whether the stars lost from clusters in the model behave like real, observed stars in the neighborhood of the Sun; 3) to test whether the force of gravity from gas clouds can explain how large clusters shrink over time, as observed clusters appear to do. An international collaboration will develop a textbook and educational resources for K-12 teachers. Two master’s students will develop graphical displays of the new models and encourage their use at public events. They plan a Hayden Planetarium Space Show to be viewed by millions around the country and the world.The investigators will study star cluster formation and destruction using a combination of multiple software tools. At the small scale, they will model cluster formation and gas expulsion with the open-source Torch software. This uses the AMUSE framework to couple the Flash adaptive mesh refinement magnetohydrodynamics code with direct N-body codes that model collisional stellar dynamics and stellar evolution codes that follow the secular evolution of each star, determining the radiative and mechanical energy they produce over time. They include a ray-tracing treatment of stellar photoionization as well as jets, winds, supernovae, radiative cooling, and self-gravity. At the large scale, they will use the SMUGGLE star formation and feedback framework in the AREPO code to determine self-consistent initial conditions and tidal fields. The scientific goals of this work are to: (1) Develop semi-analytic models that connectproperties of self-consistent dense gas clouds (a) to the resulting cluster mass, size, central concentration, and virial parameter and (b) that determine the mass loss from clusters subject to strongly fluctuating tidal forces. (2) Compare the properties of stars dispersing from low-mass clusters to the systems of moving groups, associations, and clusters observed in the Solar neighborhood, and to observations of asymmetric tidal tails from open clusters. (3) Use the semi-analytic models to follow populations of clusters through a self-consistent galactic tidal field to test the hypothesis that these tides determine the evolution from power-law mass distributions of young massive clusters to log normal distributions of old globular clusters.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.

大多数明星，包括我们自己的阳光，形成了数百至数百万星的簇。随着这些簇的年龄增长，它们很快就开始失去星星。这两者都来自恒星，并从重力互相拉动，以及近乎巨大的气云的重力。这些恒星从集群中散开，但仍以类似的速度移动。在太阳附近观察到这样的恒星一起移动。恒星用紫外线辐射，风和超新星爆炸加热气体。研究人员将使用计算机模拟研究簇如何形成和分散。拟议的工作有三个目标：1）预测将从给定的气云中形成的群集； 2）测试恒星是否从模型中的簇中损失，就像真实的，在太阳附近观察到的恒星； 3）要测试气云的重力是否可以解释簇随时间缩小的大小缩小，因为观察到的簇似乎确实如此。国际合作将为K-12教师开发教科书和教育资源。两个硕士学生将开发新模型的图形显示，并鼓励他们在公共活动中使用。他们计划了一场海顿天文馆太空展览，该节目将被全国和世界各地的数百万人所看。研究人员将使用多种软件工具的组合研究星团的形成和破坏。在小规模上，他们将使用开源火炬软件建模集群形成和煤气驱动。这使用娱乐框架将Flash自适应网状精炼磁性流体动力学代码与直接N体型代码进行融合，该代码模拟了碰撞恒星恒星动力学和恒星进化代码，并遵循每个星星的世俗演化，确定它们会随着时间而产生的辐射和机械能。它们包括对恒星光电离的射线追踪处理以及喷气机，风，超新星，辐射冷却和自我重度。在大规模上，他们将使用AREPO代码中的走私星形形成和反馈框架来确定自一致的初始条件和潮汐场。这项工作的科学目标是：（1）开发半分析模型，这些模型可以将自一致的密集气体云连接起来（a）与所得的群集质量，大小，中心浓度和病毒参数以及（b）确定群集的质量损失，这些群集损失受到强烈波动的潮汐力的质量损失。 （2）比较恒星从低质量簇分散的特性与在太阳能邻域中观察到的移动组，关联和簇的系统，以及观察到开放式群集的不对称潮汐尾巴的观察。 （3）使用半分析模型通过一个自洽的银河潮汐领域跟随集群的人群来测试以下假设：这些潮汐决定了年轻大规模群集的批量分布的演变，以记录旧全球群集的正常分布的记录。这些奖项的奖励均通过评估范围来弥补，这表明了NSF的法律范围的范围。