Collaborative Research: Chemical Cartography in the Milky Way with APOGEE

PI和他的团队致力于精确恒星元素丰度分析的大型系统调查的科学成果，该调查旨在绘制整个银河系星系盘化学的空间变化。他们在斯隆数字巡天（SDSS）-III巡天中使用了阿帕奇点天文台的银河演化实验（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。该调查涵盖了1.51-1.68微米的波长，这是一个包括来自大约15种化学元素的有用吸收线的区域，包括α，奇数和铁峰元素。从2011年到2014年为期三年的明亮时间观测活动将使APOGEE能够观测到银河系凸起、盘和晕上大约10万颗巨星，其中绝大多数恒星位于盘中。这份来自APOGEE的整个银河系恒星化学丰度数据的大型目录用于解决与银河系盘化学相关的许多关键问题。对来自APOGEE管道的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，这些元素被用来推断额外的恒星性质（逐星星间距、距离、年龄），这些性质是绘制盘中丰度和限制银河系化学演化模型所需的。这些地图提供的三维分布代表了一个数量级的改进，在包括恒星数量，探测的化学元素数量，收集的均匀性，数据的减少和校准，以及空间覆盖范围方面，包括由于尘埃的限制而从未探测过的巨大区域。作为这项工作的一部分，该小组计划发布一个附加值的APOGEE目录，其中包括距离，距离和年龄估计，沿着APOGEE关于薄盘和厚盘中大约10万颗恒星的大约15种化学元素丰度的数据，并将这些数据简化为元素丰度的多维地图。这些数据应该对更广泛的银河系化学演化建模者有重要价值。

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.