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arXiv 1602.04824astro-ph.GA
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银河系化学演化恒星模型中的质量和金属丰度要求

Mass and Metallicity Requirement in Stellar Models for Galactic Chemical Evolution Applications

Benoit Côté, Christopher West, Alexander Heger, Christian Ritter, Brian W. O'Shea, Falk Herwig, Claudia Travaglio, Sara Bisterzo

摘要:

我们使用了一个单区化学演化模型来解决这个问题,即在大质量恒星模型的网格中需要多少质量和金属丰度,以确保可靠的星系化学演化预测。我们使用了一组产量,其中包括7个质量之间的13和30 Msun,15金属之间的质量分数为0和0.03,和两个不同的残余质量处方。我们进行了几次模拟,对恒星模型的子集进行了采样,以探索不同网格分辨率的影响。来自低质量和中等质量恒星以及Ia型超新星的恒星产额已经包括在我们的模拟中,但具有固定的网格分辨率。我们将我们的结果与银河系中观测到的O,Na,Mg,Si,Ca,Ti和Mn的恒星丰度进行了比较。我们的研究结果表明,所考虑的金属丰度的范围比该范围内的金属丰度的数量更重要,这只影响我们的数值预测约0.1德克斯。我们发现,我们在[Fe/H] < -2的预测对金属丰度范围和用于产率集合中包含的最低金属丰度的质量采样非常敏感。对于任何残余质量处方,结果之间的差异可高达0.8 dex。在较高的[Fe/H],我们发现,所需的质量数取决于感兴趣的元素和剩余质量处方。在一个单调的残余质量处方中,每个模型都爆炸为核心坍缩超新星,质量分辨率平均引起0.2 dex的变化。但是,对于包括非爆炸性岛屿的残余质量处方,质量分辨率可能会导致约0.2至0.7 dex的变化,具体取决于金属丰度范围的选择。在这样的规定下,如果没有选择足够的质量,爆炸或非爆炸模型可能会被错过,导致高估或低估大质量恒星喷出的质量。

英文摘要:

We used a one-zone chemical evolution model to address the question of how many masses and metallicities are required in grids of massive stellar models in order to ensure reliable galactic chemical evolution predictions. We used a set of yields that includes seven masses between 13 and 30 Msun, 15 metallicities between 0 and 0.03 in mass fraction, and two different remnant mass prescriptions. We ran several simulations where we sampled subsets of stellar models to explore the impact of different grid resolutions. Stellar yields from low- and intermediate-mass stars and from Type Ia supernovae have been included in our simulations, but with a fixed grid resolution. We compared our results with the stellar abundances observed in the Milky Way for O, Na, Mg, Si, Ca, Ti, and Mn. Our results suggest that the range of metallicity considered is more important than the number of metallicities within that range, which only affects our numerical predictions by about 0.1 dex. We found that our predictions at [Fe/H] < -2 are very sensitive to the metallicity range and the mass sampling used for the lowest metallicity included in the set of yields. Variations between results can be as high as 0.8 dex, for any remnant mass prescription. At higher [Fe/H], we found that the required number of masses depends on the element of interest and on the remnant mass prescription. With a monotonic remnant mass prescription where every model explodes as a core-collapse supernova, the mass resolution induces variations of 0.2 dex on average. But with a remnant mass prescription that includes islands of non-explodability, the mass resolution can cause variations of about 0.2 to 0.7 dex depending on the choice of metallicity range. With such a prescription, explosive or non-explosive models can be missed if not enough masses are selected, resulting in over- or under-estimations of the mass ejected by massive stars.

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