Milky Way和矮星系中R过程星的观测
Observations of R-Process Stars in the Milky Way and Dwarf Galaxies
摘要：
本章介绍了最近的进展，在银河系的恒星晕和卫星矮星系中发现的贫金属星的r-过程元素签名的光谱观测的概述。主要的经验教训有关的起源的r-过程进行了讨论，包括所观察到的r-过程模式的普遍性和偏离普遍性之间的轻r-过程元素和锕系元素。不同的天体物理网站的r-过程的理论预期的基础上，包括常见的和罕见的超新星和中子星合并。r-过程站点之间的一个主要区别因素是它们的延迟时间分布。对详细的r-过程模式的最佳限制来自于星系晕r-过程恒星，但这些不能提供恒星诞生气体云的环境信息。研究矮星系中的r-过程富集可以弥补这种情况，尽管在这些系统中很难获得单个恒星的高分辨率光谱观测。一般概述矮星系的性质和化学演化的预期取决于它们的质量和恒星形成的持续时间。r-过程的趋势取决于恒星质量和恒星形成的矮星系的持续时间的方式，清楚地表明，r-过程是罕见的，多产的，并有即时和延迟的来源。这项工作补充了正在进行的理论重元素核合成探索和实验测量的r-过程核的性质，如与设施的稀有同位素束。
英文摘要：
This chapter presents an overview of the recent progress on spectroscopic observations of metal-poor stars with r-process element signatures found in the Milky Way's stellar halo and satellite dwarf galaxies. Major empirical lessons related to the origins of the r-process are discussed, including the universality of the observed r-process pattern and deviations from universality among the light r-process elements and actinides. Different astrophysical sites of the r-process based on theoretical expectations are presented, including common and rare supernovae and neutron star mergers. A major distinguishing factor between r-process sites is their delay time distribution. The best constraints on the detailed r-process pattern come from Galactic halo r-process stars, but these cannot provide information on the environment of the stars' birth gas clouds. Studying r-process enrichment within dwarf galaxies can remedy the situation despite the fact that high-resolution spectroscopic observations of individual stars in these systems are very difficult to obtain. A general overview of dwarf galaxy properties and chemical evolution expectations depending on their mass and star formation duration is provided. The r-process trends depend on the stellar mass and star formation durations of dwarf galaxies in a way that clearly shows that the r-process is rare, prolific, and has both prompt and delayed sources. This work complements ongoing theoretical heavy-element nucleosynthesis explorations and experimental measurements of the properties of r-process nuclei, such as with the Facility for Rare Isotope Beams.
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