Stellar Population Diagnostics of the Massive Star Binary Fraction
Stellar Population Diagnostics of the Massive Star Binary Fraction
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DOI：
10.3847/1538-4357/aae5d6
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发表时间：
2018-10
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影响因子：
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通讯作者：
T. Dorn-Wallenstein;E. Levesque
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文献类型：
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作者：
T. Dorn-Wallenstein;E. Levesque
大质量恒星的数量直接反映了恒星演化的物理学。大质量恒星亚型的计数和不同演化状态大质量恒星的比率已被广泛用作年龄和金属丰度效应的诊断。虽然大质量恒星的双星比例很重要，但推论通常基于仅包含单星演化的模型。在这项工作中，我们利用来自双星种群和恒星合成代码的定制合成恒星种群来确定恒星双星对年轻大质量星团和具有大质量恒星种群的星系中不同演化阶段的计数比的影响。我们发现许多比率在金属丰度、年龄和/或二元分数方面是简并的。我们使用这些恒星计数比率来绘制诊断图，以帮助打破这种简并性，并使用这些图将我们的预测与银河系和本星系群中的观测数据进行比较。这些数据表明大质量恒星双星分数与金属丰度之间可能存在相关性。我们还检查了我们在不同完整性水平的样本中预测的稳健性。我们发现，包含二进制文件和施加完整性限制都会导致推断年龄发生≳0.1 dex 变化。我们的结果强调了双星演化通道对巨大恒星群体的影响。
Populations of massive stars are directly reflective of the physics of stellar evolution. Counts of subtypes of massive stars and ratios of massive stars in different evolutionary states have been used ubiquitously as diagnostics of age and metallicity effects. While the binary fraction of massive stars is significant, inferences are often based upon models incorporating only single-star evolution. In this work, we utilize custom synthetic stellar populations from the Binary Population and Stellar Synthesis code to determine the effect of stellar binaries on number count ratios of different evolutionary stages in both young massive clusters and galaxies with massive stellar populations. We find that many ratios are degenerate in metallicity, age, and/or binary fraction. We develop diagnostic plots using these stellar count ratios to help break this degeneracy, and use these plots to compare our predictions to observed data in the Milky Way and the Local Group. These data suggest a possible correlation between the massive star binary fraction and metallicity. We also examine the robustness of our predictions in samples with varying levels of completeness. We find including binaries and imposing a completeness limit can both introduce ≳0.1 dex changes in inferred ages. Our results highlight the impact that binary evolution channels can have on the massive star population.