THE CH(G) INDEX AS A NEW CRITERION FOR SELECTING RED GIANT STARS
文献类型：期刊论文
| 作者 | Chen, Y. Q.; Zhao, G. ; Carrell, K.; Zhao, J. K.; Tan, K. F.
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| 刊名 | ASTROPHYSICAL JOURNAL
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| 出版日期 | 2013-03-10 |
| 卷号 | 765期号:2 |
| 关键词 | Galaxy: abundances globular clusters: general globular clusters: individual (M3, M15, M92) stars: distances stars: evolution stars: late-type |
| 英文摘要 | We have measured the CH G band (CH(G)) index for evolved stars in the globular cluster M3 based on the Sloan Digital Sky Survey (SDSS) spectroscopic survey. It is found that there is a useful way to select red giant branch (RGB) stars from the contamination of other evolved stars such as asymptotic giant branch (AGB) and red horizontal branch (RHB) stars by using the CH(G) index versus (g - r)(0) diagram if the metallicity is known from the spectra. When this diagram is applied to field giant stars with similar metallicity, we establish a calibration of CH(G) = 1.625(g - r)(0) - 1.174(g - r)(0)(2) - 0.934. This method is confirmed by stars with [Fe/H] similar to -2.3 where spectra of member stars in globular clusters M15 and M92 are available in the SDSS database. We thus extend this kind of calibration to every individual metallicity bin ranging from [Fe/H] similar to -3.0 to [Fe/H] similar to 0.0 by using field red giant stars with 0.4 <= (g - r)(0) <= 1.0. The metallicity-dependent calibrations give CH(G) = 1.625(g - r)(0) - 1.174(g - r)(0)(2) + 0.060[Fe/H] - 0.830 for - 3.0 < [Fe/H] <= - 1.2 and CH(G) = 0.953(g - r)(0) - 0.655(g - r)(0)(2) + 0.060[Fe/H] - 0.650 for - 1.2 < [Fe/H] < 0.0. The calibrations are valid for the SDSS spectroscopic data set, and they cannot be applied blindly to other data sets. With the two calibrations, a significant number of the contaminating stars (AGB and RHB stars) were excluded and thus a clear sample of red giant stars is obtained by selecting stars within +/- 0.05 mag of the calibration. The sample is published online and it is expected that this large and clean sample of RGB stars will provide new information on the formation and evolution of the Galaxy. |
| 收录类别 | SCI |
| 语种 | 英语 |
| WOS记录号 | WOS:000315921500081 |
| 源URL | [http://ir.bao.ac.cn/handle/114a11/5935]  |
| 专题 | 国家天文台_光学天文研究部 |
| 作者单位 | Chinese Acad Sci, Natl Astron Observ, Key Lab Opt Astron, Beijing 100012, Peoples R China |
| 推荐引用方式 GB/T 7714 | Chen, Y. Q.,Zhao, G.,Carrell, K.,et al. THE CH(G) INDEX AS A NEW CRITERION FOR SELECTING RED GIANT STARS[J]. ASTROPHYSICAL JOURNAL,2013,765(2). |
| APA | Chen, Y. Q.,Zhao, G.,Carrell, K.,Zhao, J. K.,&Tan, K. F..(2013).THE CH(G) INDEX AS A NEW CRITERION FOR SELECTING RED GIANT STARS.ASTROPHYSICAL JOURNAL,765(2). |
| MLA | Chen, Y. Q.,et al."THE CH(G) INDEX AS A NEW CRITERION FOR SELECTING RED GIANT STARS".ASTROPHYSICAL JOURNAL 765.2(2013). |
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来源：国家天文台
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