On the metallicity distribution of the peculiar globular cluster M22
arXiv:1608.08297 · doi:10.3847/0067-0049/226/2/16
Abstract
In our previous study, we showed that the peculiar globular cluster (GC) M22 contains two distinct stellar populations, namely the Ca-w and Ca-s groups with different physical properties, having different chemical compositions, spatial distributions and kinematics. We proposed that M22 is most likely formed via a merger of two GCs with heterogeneous metallicities in a dwarf galaxy environment and accreted later to our Galaxy. In their recent study, Mucciarelli et al. claimed that M22 is a normal mono-metallic globular cluster without any perceptible metallicity spread among the two groups of stars, which challenges our results and those of others. We devise new strategies for the local thermodynamic equilibrium (LTE) abundance analysis of red giant branch (RGB) stars in GCs and show there exists a spread in the iron abundance distribution in M22.
Accepted for publication in ApJS
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- Multiple Stellar Populations of Globular Clusters from Homogenous Ca by Photometry I. M22 (NGC 6656)
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- Multiple stellar populations of globular clusters from homogeneous Ca-Cn photometry. II. M5 (NGC 5904) and a new filter system
- Blanco DECam Bulge Survey (BDBS) II: Project Performance, Data Analysis, and Early Science Results
- Chemical Complexity in the Eu-enhanced Monometallic Globular Cluster NGC 5986
- Multiple stellar populations of globular clusters from homogeneous Ca--CN photometry. III. NGC 6752
- The CN-CH positive correlation in the globular cluster NGC 5286
- Multiple Stellar Populations of Globular Clusters From Homogeneous Ca-CN-CH-NH Photometry. VII. Metal-Poor Populations in 47 Tucanae (NGC 104)
- Five Stellar Populations in M22 (NGC 6656)
- Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC 6626)
- Nonlinear Color-Metallicity Relations of Globular Clusters. X. Subaru/FOCAS Multi-object Spectroscopy of M87 Globular Clusters