Red giant branch bump brightness in 7 metal-poor globular clusters obtained with GAIA DR2.
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| Title: | Red giant branch bump brightness in 7 metal-poor globular clusters obtained with GAIA DR2. |
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| Authors: | Song, Fen1,2 (AUTHOR) fsong@jmu.edu.cn, Yuan, Zunli3 (AUTHOR), Li, Yan2,4,5,6 (AUTHOR), Wu, Xuchao1 (AUTHOR), Pietrinferni, Adriano7 (AUTHOR), Poon, Helen8 (AUTHOR), Wu, Tao4 (AUTHOR), Nie, Jundan9 (AUTHOR), Song, Hanfeng2,10,11 (AUTHOR), Han, Cheng1 (AUTHOR), Yang, Ye1 (AUTHOR), Li, Yuxuan1 (AUTHOR), Bai, Xingming1 (AUTHOR) |
| Source: | Astrophysics & Space Science. Mar2022, Vol. 367 Issue 3, p1-12. 12p. |
| Subjects: | Red giants, Stellar luminosity function, Markov chain Monte Carlo, Probability density function, Stellar evolution, Globular clusters |
| Abstract: | The identification of the red giant branch bump brightness in metal-poor globular clusters is important for low-mass stellar evolution. The release of Gaia DR2 prompted us to revisit the red giant branch bump (RGBB) in galactic globular clusters. We apply a popular nonparametric density estimation approach, kernel density estimation (KDE), to explore the position of RGBB in 7 metal-poor globular clusters (GCs). The G and V magnitudes of the RGBB according to our clustering algorithm, G B , K and V B , K , respectively show the RGB bump magnitude detected by the KDE method in G band and V band. They show the overdensity location in the luminosity function of the RGB stars. Based on the results derived by KDE, a maximum-likelihood analysis via a Markov Chain Monte Carlo (MCMC) approach is adopted to detect the RGB bump feature and obtain more accurate RGBB brightnesses in G band and V band for the samples. We find that the red giant branch bump brightness becomes fainter as the global metallicity increases in clusters with [ M / H ] ≤ − 1.4 . We present the empirical relation between the global metallicity [ M / H ] and absolute magnitude M V of the red giant branch bump for clusters with [ M / H ] ≤ − 1.4 . We verify that discrepancies between observations and theory for metal-poor globular clusters with [ M / H ] ≤ − 1.4 . [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | The identification of the red giant branch bump brightness in metal-poor globular clusters is important for low-mass stellar evolution. The release of Gaia DR2 prompted us to revisit the red giant branch bump (RGBB) in galactic globular clusters. We apply a popular nonparametric density estimation approach, kernel density estimation (KDE), to explore the position of RGBB in 7 metal-poor globular clusters (GCs). The G and V magnitudes of the RGBB according to our clustering algorithm, G B , K and V B , K , respectively show the RGB bump magnitude detected by the KDE method in G band and V band. They show the overdensity location in the luminosity function of the RGB stars. Based on the results derived by KDE, a maximum-likelihood analysis via a Markov Chain Monte Carlo (MCMC) approach is adopted to detect the RGB bump feature and obtain more accurate RGBB brightnesses in G band and V band for the samples. We find that the red giant branch bump brightness becomes fainter as the global metallicity increases in clusters with [ M / H ] ≤ − 1.4 . We present the empirical relation between the global metallicity [ M / H ] and absolute magnitude M V of the red giant branch bump for clusters with [ M / H ] ≤ − 1.4 . We verify that discrepancies between observations and theory for metal-poor globular clusters with [ M / H ] ≤ − 1.4 . [ABSTRACT FROM AUTHOR] |
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| ISSN: | 0004640X |
| DOI: | 10.1007/s10509-022-04058-1 |
