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arXiv 2109.04031astro-ph.SRastro-ph.GA
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基于Gaia EDR3和LAMOST DR5的G和K矮星的双星分数：化学丰度的影响

Binary fractions of G and K dwarf stars based on the Gaia EDR3 and LAMOST DR5: impacts of the chemical abundances

Zexi Niu, Haibo Yuan, Song Wang, Jifeng Liu

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20 pages, 12 figures, ApJ accepted
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摘要：

基于大量的\textit{Gaia} Early Data Release 3和LAMOST Data Release 5数据，我们估算了野外晚G矮星和早K矮星的偏差校正双星分数。在这项工作中使用的恒星轨迹离群方法，它适用于各种周期和倾角的双星与单历元数据。通过一个精心挑选的，距离有限的样本，约9万GK矮星覆盖广泛的恒星化学丰度，它使我们能够探索的二元分数的变化与不同的恒星星族。整个样品的平均二元分数为0.42 $\pm$ 0.01。薄盘星的双星分数为0.39 $\pm$ 0.02，厚盘星的双星分数更高，为0.49 $\pm$ 0.02，而内晕星的双星分数可能最高。对于薄盘星和厚盘星，二元分数都朝着[Fe/H]、[ $α$ /H]和[M/H]丰度更高的方向减少。而[Fe/H]、[ $α$ /H]和[M/H]对薄盘星的抑制作用比厚盘星更显著。对于给定的[Fe/H]，[ $α$ /Fe]与薄盘星的双星分数呈正相关。然而，这种趋势消失的厚盘星。我们怀疑这可能与薄盘和厚盘的不同形成历史有关。我们的结果为二元形成的理论工作提供了新的线索。

英文摘要：

Basing on the large volume \textit{Gaia} Early Data Release 3 and LAMOST Data Release 5 data, we estimate the bias-corrected binary fractions of the field late G and early K dwarfs. A stellar locus outlier method is used in this work, which works well for binaries of various periods and inclination angles with single epoch data. With a well-selected, distance-limited sample of about 90 thousand GK dwarfs covering wide stellar chemical abundances, it enables us to explore the binary fraction variations with different stellar populations. The average binary fraction is 0.42$\pm$0.01 for the whole sample. Thin disk stars are found to have a binary fraction of 0.39$\pm$0.02, thick disk stars own a higher one of 0.49$\pm$0.02, while inner halo stars possibly own the highest binary fraction. For both the thin and thick disk stars, the binary fractions decrease toward higher [Fe/H], [$α$/H], and [M/H] abundances. However, the suppressing impacts of the [Fe/H], [$α$/H], and [M/H] are more significant for the thin disk stars than those for the thick disk stars. For a given [Fe/H], a positive correlation between [$α$/Fe] and the binary fraction is found for the thin disk stars. However, this tendency disappears for the thick disk stars. We suspect that it is likely related to the different formation histories of the thin and thick disks. Our results provide new clues for theoretical works on binary formation.

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