论文标题
带有现实不确定性的银河凸出星的年龄
The Ages of Galactic Bulge Stars with Realistic Uncertainties
论文作者
论文摘要
使用具有自定义物理学的现代同色和仔细考虑的统计技术,我们重新计算了Bensby等人提出的银河凸起中91个微镜矮人样本的年龄分布。 (2017年),并且不产生与结果一致的年龄分布。特别是,我们的分析发现,与同一样品中有42个年轻恒星的发现相比,91颗恒星中只有15个恒星年龄在7 Gyr中。虽然我们没有找到非常年轻的恒星的选区,但我们的结果确实表明存在$ \ sim8 $ gyr种群,其金属性最高,因此有助于关于年龄的长期辩论 - 银河系凸起的金属金属分布。我们通过从两个光度法,BDB和\ textit {gaia}的两个来源确定独立年龄的尝试来补充这一点,但发现光度测量的不精确性阻止了可靠的年龄和年龄不确定性确定。最后,除了标准观察不确定性外,我们还使用对全球建模不确定性的一阶考虑来得出的年龄不确定性。理论上的不确定性基于用于生成等速线的1D恒星进化模型中的自由参数的已知差异,并在包含时,导致年龄不确定性为$ 2 $ - $ 5 $ $ 5 $ GYR对于该光谱良好约束的样本。这些误差线大约是典型文献值的两倍,构成了对真实年龄不确定性的现实下限。
Using modern isochrones with customized physics and carefully considered statistical techniques, we recompute the age distribution for a sample of 91 micro-lensed dwarfs in the Galactic bulge presented by Bensby et al. (2017) and do not produce an age distribution consistent with their results. In particular, our analysis finds that only 15 of 91 stars have ages younger than 7 Gyr, compared to their finding of 42 young stars in the same sample. While we do not find a constituency of very young stars, our results do suggest the presence of an $\sim8$ Gyr population at the highest metallicities, thus contributing to long-standing debate about the age--metallicity distribution of the Galactic bulge. We supplement this with attempts at independent age determinations from two sources of photometry, BDBS and \textit{Gaia}, but find that the imprecision of photometric measurements prevents reliable age and age uncertainty determinations. Lastly, we present age uncertainties derived using a first-order consideration of global modeling uncertainties in addition to standard observational uncertainties. The theoretical uncertainties are based on the known variance of free parameters in the 1D stellar evolution models used to generate isochrones, and when included, result in age uncertainties of $2$--$5$ Gyr for this spectroscopically well-constrained sample. These error bars, which are roughly twice as large as typical literature values, constitute realistic lower limits on the true age uncertainties.