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arXiv 2309.17153astro-ph.GAastro-ph.SR
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径向迁移在Gaia DR3疏散星团与场星种群中的作用

The role of radial migration in open cluster and field star populations with Gaia dr3

Carlos Viscasillas Vázquez, Laura Magrini, Lorenzo Spina, Gražina Tautvaišienė, Mathieu Van der Swaelmen, Sofia Randich, Giuseppe Germano Sacco

备注：
13 pages, 20 figures, 2 tables. Article accepted for publication in A&A
发表信息：
A&A 679, A122 (2023)
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AI总结：

本研究通过比较Gaia DR3中疏散星团与场星的运动学演化，发现古老幸存星团因质量更大且处于高偏心率轨道而能更长时间存活。

摘要：

星团的生存时间取决于其总质量、密度及由此决定的尺寸，同时也取决于其诞生及所处环境。其动力学演化受多种因素影响，如银河系棒、旋臂结构和分子云的引力作用。总体而言，决定星团寿命的因素复杂且尚未完全理解。本研究旨在探讨疏散星团与场星对引起径向迁移的扰动是否有不同响应，特别是理解最古老幸存星团的性质。我们比较了两个Gaia DR3样本的运动学性质随时间的演化：第一个样本包含约40个疏散星团，第二个样本包含约66,000颗MSTO场星。两个样本均采用相同质量标准筛选，属于薄盘，金属丰度范围相似，位于相同的银河系中心区域[7.5-9 kpc]，且年龄大于1 Gyr。我们对场星与疏散星团样本的性质进行了统计分析。运动学与轨道性质的定性比较表明，年龄小于2-3 Gyr的星团比场星更能抵抗扰动，并沿准圆轨道运行。相反，年龄大于约3 Gyr的星团比同年龄段的孤立恒星拥有更偏心、更倾斜的轨道。这类轨道使它们在银盘上达到更高的高度，从而最大化它们多存活数个Gyr的概率。正式统计分析表明，场星与疏散星团大多数运动学和轨道性质随时间的演化存在差异。结果表明，最古老的幸存星团通常质量更大，且在更高偏心率的轨道上运行。

英文摘要：

The survival time of a star cluster depends on its total mass, density, and thus size, as well as on the environment in which it was born and in which lies. Its dynamical evolution is influenced by various factors such as gravitational effects of the Galactic bar, spiral structures, and molecular clouds. Overall, the factors that determine the longevity of a cluster are complex and not fully understood. This study aims to investigate if open clusters and field stars respond differently to the perturbations that cause radial migration. In particular, we aim at understanding the nature of the oldest surviving clusters. We compared the time evolution of the kinematic properties of two Gaia DR3 samples: the first sample is composed of $\sim$40 open clusters and the second one of $\sim$66,000 MSTO field stars. Both selected samples are composed of stars selected with the same quality criterion, belonging to the thin disc, in a similar metallicity range, located in the same Galactocentric region [7.5-9 kpc] and with ages >1 Gyr. We performed a statistical analysis comparing the properties of the samples of field stars and of open clusters. A qualitative comparison of kinematic and orbital properties reveals that clusters younger than 2-3 Gyr are more resistant to perturbations than field stars and they move along quasi-circular orbits. Conversely, clusters older than approximately 3 Gyr have more eccentric and inclined orbits than isolated stars in the same age range. Such orbits lead them to reach higher elevations on the Galactic plane, maximising their probability to survive several Gyr longer. A formal statistical analysis reveals that there are differences among the time evolution of most of the kinematic and orbital properties of field stars and open clusters. Our results suggest that oldest survived clusters are usually more massive and move on orbits with higher eccentricity.

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