The GALAH Survey: Chemodynamics of the Solar Neighbourhood
Michael R. Hayden, Joss Bland-Hawthorn, Sanjib Sharma, Ken Freeman, Janez Kos, Sven Buder, Borja Anguiano, Martin Asplund, Boquan Chen, Shourya Khanna, Jane Lin… 展开作者
Michael R. Hayden, Joss Bland-Hawthorn, Sanjib Sharma, Ken Freeman, Janez Kos, Sven Buder, Borja Anguiano, Martin Asplund, Boquan Chen, Shourya Khanna, Jane Lin, Jonathan Horner, Sarah Martell, Rosemary Wyse, Daniel Zucker, Tomaz Zwitter
We present the chemodynamic structure of the solar neighbourhood using 62 814 stars within a 500 pc sphere of the Sun observed by GALAH and with astrometric parameters from Gaia DR2. We measure the velocity dispersion for all three components (vertical, radial, and tangential) and find that it varies smoothly with [Fe/H] and [$α$/Fe] for each component. The vertical component is especially clean, with $σ_{v_z}$ increasing from a low of $8$ km s$^{-1}$ at solar-[$α$/Fe] and [Fe/H] to a high of more than 50 km s$^{-1}$ for more metal-poor and [$α$/Fe] enhanced populations. We find no evidence of a large decrease in the velocity dispersion of the higher-[$α$/Fe] populations as claimed in analysis prior to Gaia DR2, although the trend of increasing velocity dispersion with [$α$/Fe] for the same metallicity does significantly flatten at high-[$α$/Fe]. The eccentricity distribution for local stars varies most strongly as a function of [$α$/Fe], where stars with [$α$/Fe]$<0.1$ dex having generally circular orbits ($e<0.15$), while the median eccentricity increases rapidly for more [$α$/Fe]-enhanced stellar populations up to $e\sim0.35$. These [$α$/Fe]-enhanced populations have guiding radii consistent with origins in the inner Galaxy. Of the stars with metallicities much higher than the local ISM ([Fe/H]>0.1 dex), we find that more than 70\% have $e<0.2$ and are likely observed in the solar neighbourhood through churning/migration rather than blurring effects, as the epicyclic motion for these stars is not large enough to reach the radii at which they were likely born based on their metallicity.
恒星化学元素丰度测量的集合，以及精确的距离和轨道特性，为研究银河系的演化提供了高维数据。随着银河考古学与HERMES（GALAH）调查的第三次数据发布，我们发布了588571颗主要是附近恒星的678423光谱（81.2%的恒星在<2 kpc），用英澳望远镜的HERMES摄谱仪观测。这个版本（以下简称GALAH+ DR 3）包括GALAH第一阶段（亮、主、暗巡天，70%）、K2-HERMES（17%）、TESS-HERMES（5%）的所有观测结果，以及一部分辅助观测结果（8%），包括核球和>75个星团。利用改进后的光谱合成程序SME和一维MARCS模型大气，推导了恒星参数$T_\text{eff}$、$\log g$、[Fe/H]、$v_\text{mic}$、$v_\text{broad}$和$v_\text{rad}$。我们打破了光谱简并在我们的光谱分析与天体测量从$Gaia$ DR 2和测光从2 MASS。我们报告了30种不同元素（其中11种是基于非LTE计算）的丰度比[X/Fe]，涵盖了5种核合成途径。我们描述了验证的准确性和精度，特殊的明星/测量和建议使用我们的结果标记。我们的目录包括65%的矮星，34%的巨星和1%的其他/未分类的恒星。根据未标记的化学成分和年龄，我们发现62%的年轻低$α$，9%的年轻高$α$，27%的老年高$α$，和2%的恒星具有$\mathrm{[F…
StarHorse results for spectroscopic surveys + Gaia DR3: Chrono-chemical populations in the solar vicinity, the genuine thick disk, and young-alpha rich stars
