Detailed abundances of 15 stars in the metal-poor globular cluster NGC 4833
Detailed abundances of 15 stars in the metal-poor globular cluster NGC 4833
复制标题
贫金属球状星团 NGC 4833 中 15 颗恒星的详细丰度
DOI：
10.1093/mnras/stv546
复制
发表时间：
2015
影响因子：
4.8
通讯作者：
I. Thompson
中科院分区：
文献类型：
--
作者：
I. Roederer;I. Thompson
我们使用麦哲伦的麦哲伦稻盛和夫京瓷梯形摄谱仪在相对质量较大、贫金属的球状星团 NGC 4833 中观测到了 15 颗红巨星。我们计算每颗恒星的恒星参数，并进行标准丰度分析，得出 43 种 39 种元素的丰度，其中包括 20 种比铁族重的元素。我们从 Fe I 系得出 = -2.25 +/- 0.02，从 Fe II 系得出 = -2.19 +/- 0.013。我们证实了早期的结果，即 NGC 4833 中没有内部金属丰度扩散，并且铁族中的任何元素之间不存在显着的恒星间丰度分散（19 <= Z <= 30）。我们恢复了轻元素 C、N、O、Na、Mg、Al 和可能的 Si 之间的常见丰度变化。重元素分布反映了 r 过程核合成的富集 ([Eu/Fe] = +0.36 +/- 0.03)，如在许多其他贫金属球状星团中发现的那样。我们研究了中子捕获元素中发现的恒星与恒星之间的微小变化，我们得出的结论是这些可能不是真正的变化。 Th 丰度上限 log epsilon (Th/Eu) < -0.47 +/- 0.09 表明 NGC 4833 与研究 Th 的其他球状星团一样，没有经历所谓的“锕系元素增强”。
We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard abundance analysis to derive abundances of 43 species of 39 elements, including 20 elements heavier than the iron group. We derive = -2.25 +/- 0.02 from Fe I lines and = -2.19 +/- 0.013 from Fe II lines. We confirm earlier results that found no internal metallicity spread in NGC 4833, and there are no significant star-to-star abundance dispersions among any elements in the iron group (19 <= Z <= 30). We recover the usual abundance variations among the light elements C, N, O, Na, Mg, Al, and possibly Si. The heavy-element distribution reflects enrichment by r-process nucleosynthesis ([Eu/Fe] = +0.36 +/- 0.03), as found in many other metal-poor globular clusters. We investigate small star-to-star variations found among the neutron-capture elements, and we conclude that these are probably not real variations. Upper limits on the Th abundance, log epsilon (Th/Eu) < -0.47 +/- 0.09, indicate that NGC 4833, like other globular clusters where Th has been studied, did not experience a so-called "actinide boost."