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首页> 外文期刊>The Astrophysical journal >A Comparison of Elemental Abundance Ratios in Globular Clusters, Field Stars, and Dwarf Spheroidal Galaxies
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A Comparison of Elemental Abundance Ratios in Globular Clusters, Field Stars, and Dwarf Spheroidal Galaxies

机译:球状星团,场星和矮球状星系中元素丰度比的比较

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We have compiled a sample of globular clusters with high-quality stellar abundances from the literature to compare to the chemistries of stars in the Galaxy and in dwarf spheroidal galaxies. Of the 45 globular clusters examined, 29 also have kinematic information. Most of the globular clusters belong to the Galactic halo; however, a significant number have disk kinematics or belong to the bulge. Focusing on the [α/Fe] and light r-process element ratios, we find that most globular cluster stars mimic field stars of similar metallicities, and neither clearly resembles the currently available stellar abundances in dwarf galaxies (including globular clusters in the Large Magellanic Cloud). The exceptions to these general elemental ratio comparisons are already known in the literature, e.g., ω?Centauri, Palomar?12, and Terzan?7 associated with the Sagittarius remnant and Ruprecht?106, which has a high radial velocity and low [α/Fe] ratio. A few other globular clusters show more marginal peculiarities. The most notable one is the halo cluster M68, which has a high galactocentric rotational velocity, a slightly younger age, and a unique [Si/Ti] ratio. The [Si/Ti] ratios decrease with increasing [Fe/H] at intermediate metallicities, which is consistent with very massive stars playing a larger role in the early chemical evolution of the Galaxy. The chemical similarities between globular clusters and field stars with [Fe/H] ≤ -1.0 suggests a shared chemical history in a well-mixed early Galaxy. The differences in the published chemistries of stars in the dwarf spheroidal galaxies suggest that neither the globular clusters, halo stars, nor thick disk stars had their origins in small isolated systems like the present-day Milky Way dwarf satellites.
机译:我们从文献中收集了具有高质量恒星丰度的球状星团样本,以与银河系和矮球形星系中的恒星化学进行比较。在检查的45个球状星团中,有29个也具有运动学信息。大多数球状星团属于银河系光环。但是,相当多的人具有盘运动学或属于凸起。着眼于[α/ Fe]和轻r-过程元素之比,我们发现大多数球状星团都模仿相似金属性的场星,并且都没有明显类似于矮星系中的当前恒星丰度(包括大麦哲伦星系中的球状星团)云)。这些一般元素比率比较的例外在文献中是已知的,例如,与人马座残体和鲁普雷希特·106相关的ω?Centauri,Palomar?12和Terzan?7,具有较高的径向速度和较低的[α/ Fe]比。其他一些球状星团显示出更多的边缘特征。最值得注意的一个是晕星团M68,它具有较高的半中心旋转速度,稍年轻的年龄和独特的[Si / Ti]比。在中等金属状态下,[Si / Ti]比随[Fe / H]的增加而降低,这与非常大的恒星在银河系的早期化学演化中发挥更大作用相一致。 [Fe / H]≤-1.0的球状星团与田间恒星之间的化学相似性表明,在混合良好的早期星系中有共同的化学历史。矮球状星系中已发表恒星化学的差异表明,球状星团,光晕恒星和厚盘状恒星都没有起源于像今天银河系矮卫星这样的小型孤立系统。

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