Abundance Ratios in GALAH DR2 and Their Implications for Nucleosynthesis
Abundance Ratios in GALAH DR2 and Their Implications for Nucleosynthesis
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GALAH DR2 中的丰度比及其对核合成的影响
DOI：
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发表时间：
2019
影响因子：
4.9
通讯作者：
D. Weinberg
中科院分区：
文献类型：
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作者：
Emily J. Griffith;Jennifer A. Johnson;D. Weinberg
利用GALAH光学光谱调查第二次发布的70,924颗恒星的样本，我们构建了21种元素的[X/Mg]与[Mg/H]的中位数序列，通过[Mg/Fe]的切割分离出高α/“低ia”和低α/“高ia”的恒星群。之前的近红外远地点巡天工作表明，这些序列几乎与银河系盘上的位置无关，这意味着它们是由恒星核合成产量决定的，对其他化学演化方面几乎没有敏感性。两个[X/Mg]序列之间的分离表明了提示富集和延迟富集机制的相对重要性，而序列的斜率表明了产率对金属丰度的依赖性。GALAH和APOGEE的测量结果在某些共同元素上是一致的，但在序列分离或金属丰度趋势上有所不同。GALAH提供了九种新元素。我们推断大约75%的太阳C来自核心坍缩超新星，25%来自延迟机制。我们发现铁峰元素Sc、Ti、Cu和Zn的核心崩塌分数为60%-80%，核心崩塌的Cu产率具有很强的金属丰度依赖性。对于中子捕获元素Y， Ba和La，我们推断出具有非单调金属丰度依赖性的大延迟贡献。[Eu/Mg]序列的分离表明，相对于恒星的形成，至少有~ 30%的Eu富集被延迟。我们将我们的结果与几个超新星和渐近巨支产率模型的预测结果进行了比较；C、Na、K、Mn和Ca都显示出与模型的差异，这可能使它们成为核合成物理的有用诊断。
Using a sample of 70,924 stars from the second data release of the GALAH optical spectroscopic survey, we construct median sequences of [X/Mg] versus [Mg/H] for 21 elements, separating the high-α/“low-Ia” and low-α/“high-Ia” stellar populations through cuts in [Mg/Fe]. Previous work with the near-IR APOGEE survey has shown that such sequences are nearly independent of location in the Galactic disk, implying that they are determined by stellar nucleosynthesis yields with little sensitivity to other chemical evolution aspects. The separation between the two [X/Mg] sequences indicates the relative importance of prompt and delayed enrichment mechanisms, while the sequences’ slopes indicate metallicity dependence of the yields. GALAH and APOGEE measurements agree for some of their common elements, but differ in sequence separation or metallicity trends for others. GALAH offers access to nine new elements. We infer that about 75% of solar C comes from core-collapse supernovae and 25% from delayed mechanisms. We find core-collapse fractions of 60%–80% for the Fe-peak elements Sc, Ti, Cu, and Zn, with strong metallicity dependence of the core-collapse Cu yield. For the neutron capture elements Y, Ba, and La, we infer large delayed contributions with non-monotonic metallicity dependence. The separation of the [Eu/Mg] sequences implies that at least ∼30% of Eu enrichment is delayed with respect to star formation. We compare our results to predictions of several supernova and asymptotic giant branch yield models; C, Na, K, Mn, and Ca all show discrepancies with models that could make them useful diagnostics of nucleosynthesis physics.
影响因子：
4.8
作者：
I. Seitenzahl;F. Ciaraldi-Schoolmann;F. Roepke;M. Fink;W. Hillebrandt;M. Kromer;R. Pakmor;A. Ruiter-A
通讯作者：
I. Seitenzahl;F. Ciaraldi-Schoolmann;F. Roepke;M. Fink;W. Hillebrandt;M. Kromer;R. Pakmor;A. Ruiter-A
影响因子：
5.3
作者：
Blanton, Michael R.;Bershady, Matthew A.;Zou, Hu
通讯作者：
Zou, Hu
影响因子：
8.7
作者：
Fields, C. E.;Timmes, F. X.;Couch, S. M.
通讯作者：
Couch, S. M.