Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)
Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)
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DOI：
10.1093/mnras/sty150
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发表时间：
2017-10
影响因子：
4.8
通讯作者：
V. S. Aguirre;M. Bojsen-Hansen;D. Slumstrup;L. Casagrande;D. Kawata;I. Ciucă;R. Handberg;M. Lund-M.-L
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文献类型：
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作者：
V. S. Aguirre;M. Bojsen-Hansen;D. Slumstrup;L. Casagrande;D. Kawata;I. Ciucă;R. Handberg;M. Lund-M.-L
对银河系盘的起源和演化的研究长期以来一直依赖于对其组成部分的化学和运动学鉴定来重建我们银河系的过去。由于难以确定恒星的精确年龄，大多数研究都局限于小样本，通常局限于太阳附近。在这里，我们打破这一僵局的帮助下，asteroseismic推断，并执行年表的光盘的演变在整个银河系的年龄。我们化学解剖银河系盘人口使用样本的红巨星跨越到2千秒差距的开普勒卫星观测到的太阳环带，与增加的维度的小行星地震年龄。我们的研究结果揭示了低α和高α种群之间的年龄差异，这也表明了V和W分量的明显速度分散。对于高α盘星，年龄与金属丰度和[α/Fe]之间没有紧密的相关性。我们的结果表明，该组分的形成时间超过2 Gyr，[M/H]和[α/Fe]的变化范围很大，与时间无关。我们的研究结果表明，年轻的富α星的运动学性质与其他高α星群一致，与年龄相似的低α星不同，支持它们的起源是经历了质量转移或恒星合并事件的老恒星，使它们看起来更年轻，而不是在银河系附近形成的真正年轻恒星的迁移。
Investigations of the origin and evolution of the Milky Way disc have long relied on chemical and kinematic identifications of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined to the solar neighbourhood. Here, we break this impasse with the help of asteroseismic inference and perform a chronology of the evolution of the disc throughout the age of the Galaxy. We chemically dissect the Milky Way disc population using a sample of red giant stars spanning out to 2 kpc in the solar annulus observed by the Kepler satellite, with the added dimension of asteroseismic ages. Our results reveal a clear difference in age between the low- and high-α populations, which also show distinct velocity dispersions in the V and W components. We find no tight correlation between age and metallicity nor [α/Fe] for the high-α disc stars. Our results indicate that this component formed over a period of more than 2 Gyr with a wide range of [M/H] and [α/Fe] independent of time. Our findings show that the kinematic properties of young α-rich stars are consistent with the rest of the high-α population and different from the low-α stars of similar age, rendering support to their origin being old stars that went through a mass transfer or stellar merger event, making them appear younger, instead of migration of truly young stars formed close to the Galactic bar.