Photometric metallicity calibration with SDSS and SCUSS and its application to distant stars in the south Galactic cap
Photometric metallicity calibration with SDSS and SCUSS and its application to distant stars in the south Galactic cap
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SDSS 和 SCUSS 光度金属丰度校准及其在南银帽遥远恒星中的应用
DOI：
10.1093/mnras/stv1529
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发表时间：
2015
影响因子：
4.8
通讯作者：
Zhou Zhimin
中科院分区：
文献类型：
--
作者：
Gu Jiayin;Du Cuihua;Jia Yunpeng;Peng Xiyan;Wu Zhenyu;Jing Yingjie;Ma Jun;Zhou Xu;Fan Xiaohui;Fan Zhou;Jing Yipeng;Jiang Zhaoji;Lesser Michael;Nie Jundan;Shen Shiyin;Wang Jiali;Zou Hu;Zhang Tianmeng;Zhou Zhimin
基于Sloan数字巡天（SDSS）的g，r和南银帽u波段巡天（SCUSS）的u测光，利用覆盖南银帽近3700 deg（2）的32542颗F型和G型主序星的SDSS光谱，建立了一种由u-g和g-r颜色估算恒星金属丰度的光度定标方法。当g-r 0.4时，光度测定金属丰度残差相对于基于光谱的金属丰度的均方根散射为0.14 dex。由于SCUSS的u带更深、更精确，因此该估计值可用于g = 21的微弱星等。这种光度金属丰度校准的应用范围足够广泛，可以用于研究遥远恒星的金属丰度分布。本研究选取南银帽中的人马座星流及其邻近的场晕星，研究它们的金属丰度分布。我们发现，在银心柱坐标R = 19 kpc，垂线z = 14 kpc处的Sgr流呈现出相对丰富的金属丰度分布，而邻近的场晕星可以用双高斯模型来模拟，峰值分别位于[Fe/H] = -1.9和-1.5处.
Based on Sloan Digital Sky Survey (SDSS) g, r and South Galactic Cap of u-band Sky Survey (SCUSS) u photometry, we develop a photometric calibration for estimating the stellar metallicity from u - g and g - r colours by using the SDSS spectra of 32 542 F-and G-type main-sequence stars, which cover almost 3700 deg(2) in the south Galactic cap. The rms scatter of the photometric metallicity residuals relative to spectrum-based metallicity is 0.14 dex when g - r 0.4. Because of the deeper and more accurate magnitude of SCUSS u band, the estimate can be used up to the faint magnitude of g = 21. This application range of photometric metallicity calibration is wide enough so that it can be used to study metallicity distribution of distant stars. In this study, we select the Sagittarius (Sgr) stream and its neighbouring field halo stars in south Galactic cap to study their metallicity distribution. We find that the Sgr stream at the cylindrical Galactocentric coordinate of R similar to 19 kpc, vertical bar z vertical bar similar to 14 kpc exhibits a relative rich metallicity distribution, and the neighbouring field halo stars in our studied fields can be modelled by two-Gaussian model, with peaks, respectively, at [Fe/H] = -1.9 and -1.5.