Collaborative Research: Chemical Cartography in the Milky Way with APOGEE

PI和他的团队致力于研究大规模系统调查的科学结果，以进行精确的恒星元素丰度分析，以绘制整个银河系盘中化学成分的空间变化。他们在斯隆数字天空调查(SDSS)-III调查中使用了阿帕奇点天文台星系演化实验(APOEE)，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调查。这项调查涵盖了1.51-1.68微米的波长，这一区域包括来自大约15种化学元素的有用吸收线，包括阿尔法元素、奇数元素和铁峰元素。从2011年到2014年，为期三年的明亮时间观测活动将使远地点能够观测到银河系凸起、盘和光晕中约10万颗巨星，其中绝大多数恒星在盘中。从远地点到银河系的所有恒星的化学丰度数据的大型目录被用来解决一些与银盘化学有关的关键问题。对来自远地点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，这些参数被用来推断额外的恒星性质(逐星消光、距离、年龄)，这些是绘制银盘丰度图和限制银河化学演化模型所需的。这些地图提供的三维分布代表了以前在恒星数量、探测到的化学元素数量、数据收集、缩减和校准中的均质性以及空间覆盖方面所取得的进步一个数量级，其中包括由于尘埃的限制而从未探测过的大片圆盘。作为这项工作的一部分，该团队计划发布一个关于灭绝、距离和年龄估计的增值远地点目录，以及来自薄盘和厚盘的约10万颗恒星的约15种化学元素丰度的远地点数据，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模型研究人员具有重要价值。

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.