Deriving the Metallicity Distribution Function of Galactic Systems
Deriving the Metallicity Distribution Function of Galactic Systems
复制标题
推导星系系统的金属丰度分布函数
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
B. Gibson
中科院分区：
文献类型：
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作者：
Y. Fenner;B. Gibson
摘要 使用双相富金属坠落模型研究了银河系的化学演化，在该模型中，原始气体为恒星形成的最早时期提供燃料，随后由新吸积的气体不断形成恒星。该模型再现了当地 K 矮星的最新金属丰度分布，使得银河薄盘由稍微富含金属的气体形成，并具有 α 元素增强。我们的模型预测恒星晕和薄盘的年龄分别为 12.5 和 7.4 Gyr，与经验确定的值一致。本文提出的模型与 Chiappini 等人的类似双相流入模型进行了比较。 （2001）。我们讨论了简并性，该简并性使两个模型都能恢复 K 矮星金属丰度分布，同时产生不同的恒星形成历史。 K-矮星的金属丰度分布函数（MDF）被认为比 G-矮星分布更能直接与化学演化模型结果进行比较，因为质量较低的 K-矮星不太容易受到恒星演化效应的影响。因此，与广泛使用的 G 矮星 MDF 相比，K 矮星 MDF 应该是更好的恒星形成历史探测器，并对化学演化模型提供更强的约束。针对 NGC 5128 外晕的情况，量化了应用于 G 矮星 MDF 的校正。
Abstract The chemical evolution of the Milky Way is investigated using a dual-phase metal-enriched infall model in which primordial gas fuels the earliest epoch of star formation, followed by the ongoing formation of stars from newly accreted gas. The latest metallicity distribution of local K-dwarfs is reproduced by this model, which allows the Galactic thin disk to form from slightly metal-enriched gas with α-element enhancement. Our model predicts ages for the stellar halo and thin disk of 12.5 and 7.4 Gyr respectively, in agreement with empirically determined values. The model presented in this paper is compared with a similar dual-phase infall model from Chiappini et al. (2001). We discuss a degeneracy that enables both models to recover the K-dwarf metallicity distribution while yielding different star formation histories. The metallicity distribution function (MDF) of K-dwarfs is proposed to be more directly comparable to chemical evolution model results than the G-dwarf distribution because lower mass K-dwarfs are less susceptible to stellar evolutionary effects. The K-dwarf MDF should consequently be a better probe of star formation history and provide a stronger constraint to chemical evolution models than the widely used G-dwarf MDF. The corrections that should be applied to a G-dwarf MDF are quantified for the case of the outer halo of NGC 5128.