Collaborative Research: Chemical Cartography in the Milky Way with APOGEE

PI和他的团队致力于从精确的恒星元素丰度分析的大型系统调查中获得的科学成果，该调查旨在绘制整个银河系盘的化学空间变化。他们在斯隆数字巡天(SDSS)-III巡天中使用了阿帕奇点天文台银河演化实验（APOGEE），这是一项大规模、近红外（h波段）、高分辨率（R ~ 30,000）、高信噪比（100）的银河系恒星群光谱巡天。这项调查覆盖了1.51-1.68微米的波长，这个区域包含了大约15种化学元素的有用吸收线，包括α、奇数和铁峰元素。从2011年到2014年为期三年的亮时观测活动将使远地点观测到横跨银河系凸起、盘状和晕状的大约10万颗巨星，其中绝大多数恒星位于盘状。从远地点开始，整个银河系的恒星的化学丰度数据的大目录被用来解决一些与银河盘化学有关的关键问题。对远地点管道数据的分析给出了恒星参数（例如，有效温度，重力，金属丰度）和大约15种元素的丰度，这些元素用于推断额外的恒星特性（恒星之间的灭绝，距离，年龄），这些特性是绘制盘内丰度和约束银河系化学演化模型所需要的。这些地图提供的三维分布代表了在包括恒星数量、探测到的化学元素数量、收集的均匀性、数据的减少和校准以及空间覆盖范围方面取得的巨大进步，包括由于尘埃的限制而从未探测过的广阔区域。作为这项工作的一部分，该团队计划发布一份增值的APOGEE灭绝目录，距离和年龄估计，以及APOGEE关于大约10万颗恒星的15种化学元素丰度的数据，这些数据来自薄盘和厚盘，并将这些数据简化为元素丰度的多维图。这些数据对于银河系化学演化建模者来说具有重要的价值。

The PI and his team work on the scientific outcomes from the large and systematic survey for precision stellar elemental abundance analyses that is set out to map the spatial variations in the chemistry across the Milky Way Galactic disk. They employ the Apache Point Observatory Galactic Evolution Experiment (APOGEE) in the Sloan Digital Sky Survey (SDSS)-III survey, which is a large-scale, near-infrared (H-band), high-resolution (R ~ 30,000), high signal-to-noise (100) spectroscopic survey of Milky Way stellar populations. The survey covers wavelengths from 1.51-1.68 microns which is a region that includes useful absorption lines from about 15 chemical elements, including alpha, odd-numbered, and iron peak elements. A three-year bright-time observing campaign from 2011-2014 will enable APOGEE to observe about 100,000 giants stars across the Galactic bulge, disk and halo, with the vast majority of these stars in the disk. This large catalog of chemical abundance data for stars all across the Milky Way from APOGEE is used to address a number of key questions related to the chemistry of the Galactic disk.The analysis of the data from the APOGEE pipeline gives the stellar parameters (e.g., effective temperatures, gravity, metallicity) and abundances for about 15 elements which are used to deduce additional stellar properties (star-by-star extinctions, distances, ages) that are needed to map the abundances in the disk and to constrain models of Galactic chemical evolution. These maps provide the three-dimensional distributions represent an order of magnitude improvement in what has been achieved before in terms of numbers of stars included, numbers of chemical elements probed, homogeneity in the collection, reduction, and calibration of the data, and spatial coverage, including vast regions of the disk never before probed because of the limitations from dust. As part of this work, the team plans to release a value-added APOGEE catalog of extinctions, distances and age estimates, along with the APOGEE data on abundances of about 15 chemical elements for about 100,000 stars from the thin and thick disks, and the reduction of these data into multidimensional maps of elemental abundances. These data should have significant value to the wider community of Galactic chemical evolution modelers.