论文标题
银河系中星星的年龄分布凸起
The age distribution of stars in the Milky Way bulge
论文作者
论文摘要
银河凸起的年龄和化学特征与银河系的形成和进化史联系。数据驱动的方法和大型调查可以使包括凸起在内的银河系的广阔地区确定出色的年龄和精确的化学丰度。在这里，我们使用大炮的数据驱动方法，以银河系的方式推断出125,367颗恒星的年龄和丰度，并使用来自Apache Point Point Point Point Garaxy Galaxy进化实验（Apogee）DR14的光谱。我们检查了$ r _ {\ text {gal}} <3.5 $ kpc中1654个凸起星的年龄和金属性。我们专注于$ b <12^\ circ $的字段，并出现在$ l <15^\ circ $的纵向上。我们看到，与太阳能社区（$τ= 4 $ gyrs）相比，凸起的恒星平均是旧的（$τ= 8 $ gyrs），而[fe/h]的分散较大（$ \ \ \ \ \ \ 0.38 $，与0.23 dex相比）。这个年龄梯度主要来自低$α$星星。沿着银河飞机看，凸起的中央场显示了[fe/h]（$σ_{[fe/h]} \ of line of Hige Velocity（$σ_{$σ_{vr} \ of Syplane of Smalleptane in age，恒星在经度上移动，在[fe/h]中变冷，分散较少，但显示出更广泛的年龄范围。我们在凸起内看到X形的签名，其纬度为$ b = 8^\ circ $，但在$ b = 12^\ circ $。未来的Apogee和其他调查数据，具有较大的抽样，为扩展我们的方法和研究提供了更详细的研究，以对银河系模型更加限制。
The age and chemical characteristics of the Galactic bulge link to the formation and evolutionary history of the Galaxy. Data-driven methods and large surveys enable stellar ages and precision chemical abundances to be determined for vast regions of the Milky Way, including the bulge. Here, we use the data-driven approach of The Cannon, to infer the ages and abundances for 125,367 stars in the Milky Way, using spectra from Apache Point Observatory Galaxy Evolution Experiment (APOGEE) DR14. We examine the ages and metallicities of 1654 bulge stars within $R_{\text{GAL}}<3.5$ kpc. We focus on fields with $b<12^\circ$, and out to longitudes of $l<15^\circ$. We see that stars in the bulge are about twice as old ($τ=8$ Gyrs), on average, compared to those in the solar neighborhood ($τ=4$ Gyrs), with a larger dispersion in [Fe/H] ($\approx0.38$ compared to 0.23 dex). This age gradient comes primarily from the low-$α$ stars. Looking along the Galactic plane, the very central field in the bulge shows by far the largest dispersion in [Fe/H] ($σ_{[Fe/H]}\approx0.4$ dex) and line of sight velocity ($σ_{vr}\approx90$ km/s), and simultaneously the smallest dispersion in age. Moving out in longitude, the stars become kinematically colder and less dispersed in [Fe/H], but show a much broader range of ages. We see a signature of the X-shape within the bulge at a latitude of $b=8^\circ$, but not at $b=12^\circ$. Future APOGEE and other survey data, with larger sampling, affords the opportunity to extend our approach and study in more detail, to place stronger constraints on models of the Milky Way.
