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THE METALLICITY GRADIENT OF THE THICK DISK BASED ON RED HORIZONTAL-BRANCH STARS FROM SDSS DR8
Chen, Y. Q.; Zhao, G.; Carrell, K.; Zhao, J. K.
2011-12-01
发表期刊ASTRONOMICAL JOURNAL
卷号142期号:6
摘要Based on SDSS DR8, we have selected a sample of 1728 red horizontal-branch (RHB) stars with vertical bar Z vertical bar < 3 kpc by using a color-metallicity relation and stellar parameters. The sample stars clearly trace a typical thick disk population with peaks at vertical bar Z vertical bar = 1.26 kpc and [Fe/H] = -0.54. The vertical metallicity gradient of the thick disk is estimated in two ways. One is a fit to the Gaussian peaks of the metallicity histograms of the thick disk by subtracting minor contributions from the thin disk and the inner halo based on the Besan, con Galaxy Model. The resulting gradient is -0.12 +/- 0.01 dex kpc(-1) for 0.5 < vertical bar Z vertical bar < 3 kpc. The other method is to linearly fit the data based on stars with 1 < vertical bar Z vertical bar < 3 kpc being the main component of the thick disk. Five subgroups are then selected in different directions in the X-vertical bar Z vertical bar plane to investigate the difference in the vertical metallicity gradient between the Galactocenter and anti-Galactocenter directions. We found that a vertical gradient of -0.22 +/- 0.07 dex kpc(-1) is detected for five directions except for one involving the pollution of stars from the bulge. The results indicate that the vertical gradient is dominant, but a radial gradient has a minor contribution for the thick disk population represented by RHB stars with 1 < vertical bar Z vertical bar < 3 kpc. The present work strongly suggests the existence of a metallicity gradient in the thick disk, which is thought to be negligible in most previous works in the literature.
关键词Galaxy: Disk Galaxy: Kinematics And Dynamics Galaxy: Structure Stars: Horizontal-branch Stars: Late-type
DOI10.1088/0004-6256/142/6/184
收录类别SCI
语种英语
WOS记录号WOS:000297254500006
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被引频次:23[WOS]   [WOS记录]     [WOS相关记录]
文献类型期刊论文
条目标识符http://ir.bao.ac.cn/handle/114a11/8010
专题光学天文研究部
作者单位Chinese Acad Sci, Key Lab Opt Astron, Natl Astron Observ, Beijing 100012, Peoples R China
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Chen, Y. Q.,Zhao, G.,Carrell, K.,et al. THE METALLICITY GRADIENT OF THE THICK DISK BASED ON RED HORIZONTAL-BRANCH STARS FROM SDSS DR8[J]. ASTRONOMICAL JOURNAL,2011,142(6).
APA Chen, Y. Q.,Zhao, G.,Carrell, K.,&Zhao, J. K..(2011).THE METALLICITY GRADIENT OF THE THICK DISK BASED ON RED HORIZONTAL-BRANCH STARS FROM SDSS DR8.ASTRONOMICAL JOURNAL,142(6).
MLA Chen, Y. Q.,et al."THE METALLICITY GRADIENT OF THE THICK DISK BASED ON RED HORIZONTAL-BRANCH STARS FROM SDSS DR8".ASTRONOMICAL JOURNAL 142.6(2011).
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