The Metal-Rich Universe: Formation and evolution of the Galactic bulge: constraints from stellar abundances
The Metal-Rich Universe: Formation and evolution of the Galactic bulge: constraints from stellar abundances
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富含金属的宇宙：银河核球的形成和演化：恒星丰度的限制
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
L. Origlia
中科院分区：
文献类型：
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作者：
S. Ballero;F. Matteucci;L. Origlia
目标。我们在银河系形成的由内而外模型的背景下计算银河核球的化学演化。该模型包含大质量恒星的最新恒星产量。本文的主要目的是将该模型的预测与化学丰度比和金属丰度分布的新观测结果进行比较，以限制凸起的形成和演化。方法。我们计算了几种α元素和Fe的演化，并通过改变不同的参数（例如恒星形成效率、初始质量函数的斜率和坠落时间尺度）进行了多次测试。我们还测试了采用大质量恒星的初级氮贡献的效果。结果。预计凸起中的 [a/Fe] 丰度比在 [Fe/H] 的很大范围内处于超太阳范围，每种元素具有不同的斜率。这些预测与最近准确的丰度测定非常一致。我们还发现了最新的核球恒星金属丰度分布的良好拟合。结论。我们得出的结论是，核球形成的时间尺度非常短（尽管排除了远小于~0.1 Gyr的时间尺度），具有相当高的恒星形成效率v≃20 Gyr -1，并且初始质量函数比太阳邻域和盘的其余部分更倾向于高质量（即x≤0.95）。这里获得的结果比以前的结果更加稳健，因为它们基于非常准确的丰度测量。
Aims. We compute the chemical evolution of the Galactic bulge in the context of an inside-out model for the formation of the Milky Way. The model contains updated stellar yields from massive stars. The main purpose of the paper is to compare the predictions of this model with new observations of chemical abundance ratios and metallicity distributions in order to put constraints on the formation and evolution of the bulge. Methods. We computed the evolution of several α-elements and Fe and performed several tests by varying different parameters such as star formation efficiency, slope of the initial mass function and infall timescale. We also tested the effect of adopting a primary nitrogen contribution from massive stars. Results. The [a/Fe] abundance ratios in the Bulge are predicted to be supersolar for a very large range in [Fe/H], each element having a different slope. These predictions are in very good agreement with most recent accurate abundance determinations. We also find a good fit of the most recent Bulge stellar metallicity distributions. Conclusions. We conclude that the Bulge formed on a very short timescale (even though timescales much shorter than ∼0.1 Gyr are excluded) with a quite high star formation efficiency of v ≃ 20 Gyr -1 and with an initial mass function more skewed toward high masses (i.e. x ≤ 0.95) than the solar neighbourhood and rest of the disk. The results obtained here are more robust than previous ones since they are based on very accurate abundance measurements.