THE SEGUE K GIANT SURVEY. II. A CATALOG OF DISTANCE DETERMINATIONS FOR THE SEGUE K GIANTS IN THE GALACTIC HALO
THE SEGUE K GIANT SURVEY. II. A CATALOG OF DISTANCE DETERMINATIONS FOR THE SEGUE K GIANTS IN THE GALACTIC HALO
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DOI：
10.1088/0004-637x/784/2/170
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发表时间：
2012-11
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通讯作者：
X. Xue;Zhibo Ma;H. Rix;H. Morrison;P. Harding;T. Beers;I. Ivans;H. Jacobson;Jennifer Johnson;Y. S. Lee;S. Lucatello;C. Rockosi;J. Sobeck;B. Yanny;Gang Zhao;C. Prieto
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作者：
X. Xue;Zhibo Ma;H. Rix;H. Morrison;P. Harding;T. Beers;I. Ivans;H. Jacobson;Jennifer Johnson;Y. S. Lee;S. Lucatello;C. Rockosi;J. Sobeck;B. Yanny;Gang Zhao;C. Prieto
我们提出了一个在线目录的距离测定6036 K巨星，其中大部分是银河系的恒星晕的成员。它们的中等分辨率光谱来自斯隆数字巡天/斯隆银河系理解和探索扩展，用于推导金属丰度和粗略的重力估计，沿着径向速度。距离模数是通过比较每颗星星的视星等与经验校准的色-光度基准点的绝对星等，在观测到的（g − r）0色和光谱[Fe/H]下得出的。我们采用了一种概率方法，使其简单地正确传播的金属性，幅度和颜色的误差到距离的不确定性。我们还折叠在以前的信息有关的巨型分支光度函数和不同的金属丰度分布的SEGUE K-巨星的目标子类别。我们发现，金属丰度先验在距离估计中起着很小的作用，但忽略光度先验可能会导致系统的距离模量偏差高达0.25等，相比使用光度先验的情况。我们发现一个中位数的距离精度为16%，距离估计最精确的最少的金属贫恒星附近的红巨星分支的尖端。我们的距离估计的精度和准确性与球状星团和疏散星团的观测进行了验证。我们目录中的恒星距离银河系中心高达125千秒差距，其中283颗恒星超过50千秒差距，形成了银河系晕中最大的远距离示踪剂光谱样本。
We present an online catalog of distance determinations for 6036 K giants, most of which are members of the Milky Way's stellar halo. Their medium-resolution spectra from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration are used to derive metallicities and rough gravity estimates, along with radial velocities. Distance moduli are derived from a comparison of each star's apparent magnitude with the absolute magnitude of empirically calibrated color–luminosity fiducials, at the observed (g − r)0 color and spectroscopic [Fe/H]. We employ a probabilistic approach that makes it straightforward to properly propagate the errors in metallicities, magnitudes, and colors into distance uncertainties. We also fold in prior information about the giant-branch luminosity function and the different metallicity distributions of the SEGUE K-giant targeting sub-categories. We show that the metallicity prior plays a small role in the distance estimates, but that neglecting the luminosity prior could lead to a systematic distance modulus bias of up to 0.25 mag, compared to the case of using the luminosity prior. We find a median distance precision of 16%, with distance estimates most precise for the least metal-poor stars near the tip of the red giant branch. The precision and accuracy of our distance estimates are validated with observations of globular and open clusters. The stars in our catalog are up to 125 kpc from the Galactic center, with 283 stars beyond 50 kpc, forming the largest available spectroscopic sample of distant tracers in the Galactic halo.