THE METALLICITY DISTRIBUTION FUNCTIONS OF SEGUE G AND K DWARFS: CONSTRAINTS FOR DISK CHEMICAL EVOLUTION AND FORMATION
THE METALLICITY DISTRIBUTION FUNCTIONS OF SEGUE G AND K DWARFS: CONSTRAINTS FOR DISK CHEMICAL EVOLUTION AND FORMATION
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DOI：
10.1088/0004-637x/761/2/160
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发表时间：
2011-12
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通讯作者：
K. Schlesinger;Jennifer A. Johnson;C. Rockosi;Y. S. Lee;H. Morrison;R. Schoenrich;C. Allende Prieto-C.-Allende-Pri
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作者：
K. Schlesinger;Jennifer A. Johnson;C. Rockosi;Y. S. Lee;H. Morrison;R. Schoenrich;C. Allende Prieto-C.-Allende-Pri
基于斯隆星系理解与探索扩展（SEGUE）调查的光谱，我们给出了距离银面0.2 ~ 2.3 kpc的24,270 G和16,847 K矮星的金属丰度分布函数（MDF）。这个恒星样本在数量和体积上都比以前的光谱分析要大得多，之前的光谱分析仅限于太阳附近，这使它成为与当地体积有限的样本和银河系模型进行比较的理想选择。我们首次修正了由SEGUE目标选择策略引入的各种观测偏差的MDF。SEGUE特别值得注意的是它的K矮星样本，这些样本太暗了，无法在远离太阳附近的地方进行光谱检测。随着|Z|的增加，两种光谱类型的MDF都变得更加缺乏金属，这反映了在小高度具有小[α/Fe]值的样品向在1 kpc以上具有增强[α/Fe]值的样品的转变。将我们的SEGUE分布与两个不同的银河系模型的分布进行比较，发现两者在平面以上的所有高度都比我们观察到的分布更富金属。我们对G矮星和K矮星的无偏观测为化学和动态星系演化模型提供了有价值的银河系盘|- Z - |-高度范围的限制，以前只校准到太阳附近，特别适用于薄盘和厚盘形成模型。
We present the metallicity distribution function (MDF) for 24,270 G and 16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based on spectroscopy from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey. This stellar sample is significantly larger in both number and volume than previous spectroscopic analyses, which were limited to the solar vicinity, making it ideal for comparison with local volume-limited samples and Galactic models. For the first time, we have corrected the MDF for the various observational biases introduced by the SEGUE target-selection strategy. SEGUE is particularly notable for its sample of K dwarfs, which are too faint to examine spectroscopically far from the solar neighborhood. The MDF of both spectral types becomes more metal-poor with increasing |Z|, which reflects the transition from a sample with small [α/Fe] values at small heights to one with enhanced [α/Fe] above 1 kpc. Comparison of our SEGUE distributions to those of two different Milky Way models reveals that both are more metal-rich than our observed distributions at all heights above the plane. Our unbiased observations of G and K dwarfs provide valuable constraints over the |Z|-height range of the Milky Way disk for chemical and dynamical Galaxy evolution models, previously only calibrated to the solar neighborhood, with particular utility for thin- and thick-disk formation models.