arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 1106.3174astro-ph.SR
收藏

球状星团NGC 1851中的多个恒星星族

Multiple stellar populations in the globular cluster NGC 1851

Eugenio Carretta, Sara Lucatello, Raffaele Gratton, A. Bragaglia, Valentina D'Orazi

备注：
25 pages, 28 figures, 13 tables (7 in electronic form only). Accepted for publication on Astronomy and Astrophysics
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

[摘要]详细的化学标记的个别恒星星族在银河系球状星团（GC）NGC 1851。丰度是从火焰光谱中获得的最大样本的巨人（124）在这个特殊的GC分析使用O，Na，Mg，Al，Si，Ca，Ti，Sc，V，Mn，Co，Ni，Cu，Y，Zr，Ba，La，Ce，Nd，Eu，Dy。我们确认了[Fe/H]在该GC中的扩散，但太小而不能清楚地分离不同的亚群。相反，我们提出了一个分类使用铁和钡的组合（更丰富的金属丰富的组）通过聚类分析：我们分为富金属（MR）和贫金属（MP）人口的恒星，他们每个人都表现出一个Na-O的关系，签名的真正GC，虽然与不同的比例的原始污染的恒星。比值[alpha/H]追踪铁，在MR人口中更高，这表明核心塌陷超新星的额外贡献。与MP相比，MR人群显示出更大的s-过程元素富集。这可能是由于中低质量恒星的贡献，因为我们发现在MR星中，重s过程元素的能级大于轻s过程核的能级;然而，低质量恒星的大贡献是不可能的，因为它可能会抵消O-Na的关系。我们还证实了之前由其他研究发现的p-捕获和s-过程元素之间的相关性的存在，至少对于MR人群。这一发现显然需要一个相当长的延迟为第二代的MR组件。两个不同的GC合并在一个母矮星系中，每一个都有不同的Ba水平和~1 Gyr的年龄差，这可能解释（i）双SGB，（ii）两个原始GC之间C含量的可能差异，以及（iii）这个特殊GC的Stromgren测光。

英文摘要：

[Abridged] Detailed chemical tagging of individual stellar populations in the Galactic globular cluster (GC) NGC 1851 is presented. Abundances are derived from FLAMES spectra for the largest sample of giants (124) ever analysed in this peculiar GC using O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Mn, Co, Ni, Cu, Y, Zr, Ba, La, Ce, Nd, Eu, Dy. We confirm a [Fe/H] spread in this GC, but too small to clearly separate different sub-populations. We instead propose a classification using a combination of Fe and Ba (much more abundant in the more metal-rich group) through a cluster analysis: we separated stars into a metal-rich (MR) and a metal-poor (MP) populations, each of them showing a Na-O anticorrelation, signature of genuine GC, although with different ratios of primordial to polluted stars. The ratio [alpha/H] tracks iron and is higher in the MR population, suggesting an additional contribution by core-collapse supernovae. The MR population shows a larger enrichment in s-process elements compared to the MP one. This is probably due to the contribution by intermediate-low mass stars, because we find that the level of heavy s-process elements is larger than the level of light s-process nuclei in the MR stars; however, a large contribution by low mass stars is unlikely, because it would likely cancel the O-Na anticorrelation. We also confirm the presence of correlations between p-capture and s-process elements previously found by other studies, at least for the MR population. This finding apparently requires a quite long delay for the second generation of the MR component. A merger of two distinct GCs in a parent dwarf galaxy, each one with a different Ba level and an age difference of ~1 Gyr, might explain (i) the double SGB, (ii) a possible difference in C content between the two original GCs, and (iii) the Stromgren photometry of this peculiar GC.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑