Chemical Cartography with APOGEE: Mapping Disk Populations with a 2-process Model and Residual Abundances
Chemical Cartography with APOGEE: Mapping Disk Populations with a 2-process Model and Residual Abundances
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DOI：
10.3847/1538-4365/ac6028
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发表时间：
2021-08
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通讯作者：
D. Weinberg;J. Holtzman;Jennifer A. Johnson;C. Hayes;S. Hasselquist;M. Shetrone;Y. Ting 丁;R. Beaton;T. Beers;J. Bird;D. Bizyaev;M. Blanton;K. Cunha;J. G. Fernández-Trincado;P. Frinchaboy;D. A. García-Hernández;Emily J. Griffith;James W. Johnson;H. Jönsson;R. Lane;Henry W. Leung;J. Mackereth;S. Majewski;S. Mészáros;C. Nitschelm;K. Pan;R. Schiavon;D. Schneider;M. Schultheis;V. Smith;J. Sobeck;K. Stassun;G. Stringfellow;F. Vincenzo;John C. Wilson;G. Zasowski
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作者：
D. Weinberg;J. Holtzman;Jennifer A. Johnson;C. Hayes;S. Hasselquist;M. Shetrone;Y. Ting 丁;R. Beaton;T. Beers;J. Bird;D. Bizyaev;M. Blanton;K. Cunha;J. G. Fernández-Trincado;P. Frinchaboy;D. A. García-Hernández;Emily J. Griffith;James W. Johnson;H. Jönsson;R. Lane;Henry W. Leung;J. Mackereth;S. Majewski;S. Mészáros;C. Nitschelm;K. Pan;R. Schiavon;D. Schneider;M. Schultheis;V. Smith;J. Sobeck;K. Stassun;G. Stringfellow;F. Vincenzo;John C. Wilson;G. Zasowski
我们对APOGEE-2的最终数据发布（DR17）中34,410颗银河系盘状恒星的16种元素丰度进行了新的统计分析。在最近工作的基础上，我们用一个两过程模型拟合中位数丰度比趋势[X/Mg]与[Mg/H]，该模型将丰度模式分解为“提示”成分追踪核心坍缩超新星和“延迟”成分追踪Ia型超新星。对于每个样本恒星，我们拟合这两个分量的振幅，然后计算残差Δ[X/H]从这两个参数拟合。最精确测量远地点丰度的均方根残差范围从~ 0.01-0.03指数到Na、V和Ce的~ 0.1指数。残差的相关性揭示了一个复杂的潜在结构，包括一个由Ca、Na、Al、K、Cr和Ce组成的相关元素组，以及一个由Ni、V、Mn和Co组成的独立元素组。选择两过程模型拟合不理想的恒星会揭示出各种各样的物理异常值，有时还会产生细微的测量误差。剩余丰度允许对金属丰度和[α/Fe]差异控制的种群进行比较。相对于主盘（R = 3-13 kpc），我们发现外盘（R = 15-17 kpc）的丰度模式几乎相同，LMC和Gaia Sausage/Enceladus恒星中多种元素的指数下降了0.05-0.2，而ω Cen中多种元素的指数偏差很大（0.4-1指数）。剩余丰度分析为发现化学上独特的恒星和恒星群，经验上限制核合成产量，以及测试化学进化模型提供了新的机会，这些模型包括元素生产和再分配中的随机性。
We apply a novel statistical analysis to measurements of 16 elemental abundances in 34,410 Milky Way disk stars from the final data release (DR17) of APOGEE-2. Building on recent work, we fit median abundance ratio trends [X/Mg] versus [Mg/H] with a 2-process model, which decomposes abundance patterns into a “prompt” component tracing core-collapse supernovae and a “delayed” component tracing Type Ia supernovae. For each sample star, we fit the amplitudes of these two components, then compute the residuals Δ[X/H] from this two-parameter fit. The rms residuals range from ∼0.01–0.03 dex for the most precisely measured APOGEE abundances to ∼0.1 dex for Na, V, and Ce. The correlations of residuals reveal a complex underlying structure, including a correlated element group comprised of Ca, Na, Al, K, Cr, and Ce and a separate group comprised of Ni, V, Mn, and Co. Selecting stars poorly fit by the 2-process model reveals a rich variety of physical outliers and sometimes subtle measurement errors. Residual abundances allow for the comparison of populations controlled for differences in metallicity and [α/Fe]. Relative to the main disk (R = 3–13 kpc), we find nearly identical abundance patterns in the outer disk (R = 15–17 kpc), 0.05–0.2 dex depressions of multiple elements in LMC and Gaia Sausage/Enceladus stars, and wild deviations (0.4–1 dex) of multiple elements in ω Cen. The residual abundance analysis opens new opportunities for discovering chemically distinctive stars and stellar populations, for empirically constraining nucleosynthetic yields, and for testing chemical evolution models that include stochasticity in the production and redistribution of elements.