标题： 星团天琴座I核心区域的初始质量函数及其他恒星特性 显示英文标题

标题： The Initial Mass Function and Other Stellar Properties Across the Core of the Hydra I Cluster

摘要： 猎犬座I星系团为研究和比较其两个最亮星系核心中的遗迹古老恒星种群提供了绝佳机会。 此外，这两个星系的动力学差异允许对一般尺度关系的局部有效性进行检验。 在本工作中，我们利用新的高质量长缝光学和近红外光谱数据进行了直接比较。 我们在每个星系中获取了大约12千秒差距范围内的年龄、金属量和19种元素丰度，以及其中心区域的初始质量函数。 我们的结果表明，尽管这两个星系的质量不同，但它们内部5千秒差距区域是在同一时间形成的，并以相似的恒星形成时间尺度和化学富集演化，证实了它们在星系团形成过程中的早期形成。 只有整体金属量和初始质量函数的径向分布显示出与它们不同的速度弥散分布相关的差异。 初始质量函数的径向趋势与[Z/H]和速度弥散呈正相关。 虽然初始质量函数与金属量的趋势对于两个星系都符合全局趋势，但与速度弥散的趋势则表现出差异。 外区显示出混合恒星种群的迹象，与中心区域相比化学成分有较大差异，但具有相似的古老年龄。 显示英文摘要

摘要： The Hydra I cluster offers an excellent opportunity to study and compare the relic old stellar populations in the core of its two brightest galaxies. In addition, the differing kinematics of the two galaxies allows a test of the local validity of general scaling relations. In this work we present a direct comparison employing full spectral fitting of new high-quality long-slit optical and NIR spectroscopic data. We retrieve age, metallicity and 19 elemental abundances out to about 12 kpc within each galaxy, as well as the IMF in their central regions. Our results suggest that the inner 5 kpc region of both galaxies, despite their different masses, formed at the same time and evolved with a similar star formation time-scale and chemical enrichment, confirming their early formation in the cluster build up. Only the overall metallicity and IMF radial profiles show differences connected with their different velocity dispersion profiles. The radial trend of the IMF positively correlates with both [Z/H] and velocity dispersion. While the trends of the IMF with metallicity agree with a global trend for both galaxies, the trends with the velocity dispersion exhibit differences. The outer regions show signs of mixed stellar populations with large differences in chemical content compared to the centers, but with similar old ages.