Tracing Birth Properties of Stars with Abundance Clustering
Tracing Birth Properties of Stars with Abundance Clustering
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DOI：
10.3847/1538-4357/ac3481
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发表时间：
2021-07
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影响因子：
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通讯作者：
B. Ratcliffe;M. Ness;T. Buck;K. Johnston;B. Sen;Leandro Beraldo e Silva;V. Debattista
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作者：
B. Ratcliffe;M. Ness;T. Buck;K. Johnston;B. Sen;Leandro Beraldo e Silva;V. Debattista
为了了解银河盘的形成和演化，我们必须将它的当前性质与它的过去联系起来。我们利用流体力学宇宙学模拟来研究恒星的化学丰度如何与它们的起源联系起来。利用两个类似银河系的模拟中丰度测量的层次聚类，以及分布和稳定的恒星形成历史，我们发现化学上相似的恒星群在出生地点(R出生)和时间(年龄)上由不同的群组成。模拟观测丰度误差(0.05Dex)，我们发现要追踪不同的(R出生，年龄)组，需要一个很大的丰度矢量。利用15个元素丰度(Fe、O、Mg、S、Si、C、P、Mn、Ne、Al、N、V、Ba、Cr、Co)，可以定义多达10个≈组与≈25%重叠(R出生、年龄)。我们建立了一个简单的模型来表明，在这些模拟的背景下，可以从丰度推断恒星的年龄和R出生，精度分别为±0.06Gyr和±1.17kpc。我们发现，丰度集群对于第三个模拟是无效的，在第三个模拟中，低α恒星形成分布在盘中，早期高α恒星形成更快的团块，随着其组成恒星的演化以丰富星际介质，这些团块向银河系中心下沉。然而，这种形成路径导致了在[α/Fe]-[Fe/H]平面上的大的年龄分散，这与银河系的观测性质不一致。我们得出结论，丰度聚类法是绘制银河系历史的一种很有前途的方法。
To understand the formation and evolution of the Milky Way disk, we must connect its current properties to its past. We explore hydrodynamical cosmological simulations to investigate how the chemical abundances of stars might be linked to their origins. Using hierarchical clustering of abundance measurements in two Milky Way–like simulations with distributed and steady star formation histories, we find that groups of chemically similar stars comprise different groups in birth place (R birth) and time (age). Simulating observational abundance errors (0.05 dex), we find that to trace distinct groups of (R birth, age) requires a large vector of abundances. Using 15 element abundances (Fe, O, Mg, S, Si, C, P, Mn, Ne, Al, N, V, Ba, Cr, Co), up to ≈10 groups can be defined with ≈25% overlap in (R birth, age). We build a simple model to show that in the context of these simulations, it is possible to infer a star’s age and R birth from abundances with precisions of ±0.06 Gyr and ±1.17 kpc, respectively. We find that abundance clustering is ineffective for a third simulation, where low-α stars form distributed in the disk and early high-α stars form more rapidly in clumps that sink toward the Galactic center as their constituent stars evolve to enrich the interstellar medium. However, this formation path leads to large age dispersions across the [α/Fe]–[Fe/H] plane, which is inconsistent with the Milky Way’s observed properties. We conclude that abundance clustering is a promising approach toward charting the history of our Galaxy.