A MUSE view on the formation of multiple populations in Globular Clusters: Observational constraints from chemistry, binaries, and kinematics

关于球状星团中多个族群形成的 MUSE 观点：来自化学、双星和运动学的观测限制

• 批准号: 498537028
• 负责人: Dr. Marilyn Latour
• 金额: --
• 依托单位: Institut für Astrophysik und Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/498537028?language=en
• 关键词: MUSE; view; formation; multiple; populations

As part of the Guaranteed Time Observations with the integral field spectrograph MUSE, we have observed the central regions of 26 Galactic Globular clusters (GCs) at multiple epochs, thus collecting more than 2 million individual stellar spectra. This invaluable dataset has been used by our group to characterize, for example, kinematics, binarity, and metallicity properties of individual clusters. An intriguing aspect of globular clusters is the presence of so-called multiple populations. For a long time, GCs have been considered perfect examples of a single stellar population consisting of stars having the same age and the same chemical composition. However, upon closer inspection, the situation appears to be more complex. It has now been shown that almost all GCs older than 2 Gyrs contain multiple populations, albeit with various properties. The stars belonging to the different populations are characterized by varying abundances of certain elements (e.g., N, O, Na) following particular correlations. By combining the information inferred from the photometric colors of red giant branch (RGB) stars with their spectroscopic properties from the MUSE spectra, we will investigate the chemical, kinematic, and binary properties of the populations in GCs included in our survey. In a first time, we will focus our efforts to make a thorough analysis of four priority clusters, NGC 1851, NGC 6752, NGC 7078, and Omega Centauri. This sample of clusters is representative of different phenomena linked to multiple populations, ranging from ``bona fide'' GCs consisting of two main populations to more complex clusters with alleged (NGC 1851) and confirmed (NGC 5139) iron spreads. In a second time, we will work on the remaining 16 clusters for which we have the photometry needed to separate the population. Work on these clusters includes optimizing the separation of RGB stars into their respective populations, comparing binary fractions between populations, and quantifying iron-spread in metal-complex clusters Our work will provide new observational constraints on key aspects that will help to better understand the origin of multiple populations in GCs. This is still an open debate where theories are numerous and characterizing populations' properties homogeneously is most helpful to constrain some of the formation scenarios.

作为积分场谱仪MUSE保证时间观测的一部分，我们在多个历元观测了26个银河系球状星团(GC)的中心区，从而收集了200多万个单独的恒星光谱。这个无价的数据集已经被我们的小组用来表征，例如，单个星系团的运动学、二元性和金属丰度属性。球状星团的一个耐人寻味的方面是所谓的多种群的存在。长期以来，GC一直被认为是由年龄相同、化学成分相同的恒星组成的单一恒星群的完美例子。然而，仔细观察，情况似乎更加复杂。现在已经表明，几乎所有超过2个回环的GC都包含多个种群，尽管具有不同的性质。属于不同星群的恒星具有不同的某些元素(如N、O、Na)丰度的特征，遵循特定的相关性。通过将从红巨星(RGB)的光度学颜色推断的信息与它们从缪斯光谱中获得的光谱性质相结合，我们将研究我们调查中包括的GC中的群体的化学、运动学和双星性质。第一次，我们将集中精力对四个优先星系团--NGC1851、NGC6752、NGC7078和半人马座欧米茄--进行彻底的分析。这种集群样本代表了与多个种群有关的不同现象，从由两个主要种群组成的“真正的”GC到据称(NGC 1851)和确认(NGC 5139)铁扩散的更复杂的集群。在第二次，我们将对剩余的16个星系团进行工作，我们拥有分离种群所需的光度学。在这些星系团上的工作包括优化将RGB恒星分离成它们各自的群体，比较群体之间的二进制分数，以及量化金属络合物星系团中的铁扩散。我们的工作将在关键方面提供新的观测约束，这将有助于更好地理解GC中多个群体的起源。这仍然是一场公开的辩论，理论数不胜数，对种群特性的同质性描述最有助于限制某些形成情景。