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New Subgrouping of Multiple Stellar Populations in NGC 2808 Based on Low-resolution Spectroscopy
- Title
- New Subgrouping of Multiple Stellar Populations in NGC 2808 Based on Low-resolution Spectroscopy
- Authors
- Hong, Seungsoo; Lim, Dongwook; Chung, Chul; Kim, Jaeyeon; Han, Sang-Il; Lee, Young-Wook
- Ewha Authors
- 한상일
- SCOPUS Author ID
- 한상일
- Issue Date
- 2021
- Journal Title
- ASTRONOMICAL JOURNAL
- ISSN
- 0004-6256
1538-3881
- Citation
- ASTRONOMICAL JOURNAL vol. 162, no. 4
- Publisher
- IOP PUBLISHING LTD
- Indexed
- SCIE; SCOPUS
- Document Type
- Article
- Abstract
- We performed low-resolution spectroscopy for the red giant branch stars in an intriguing globular cluster (GC) NGC 2808, which hosts subpopulations with extreme helium and light-element abundances. In order to trace N, C, and Ca abundance differences among subpopulations, we measured CN, CH, and Ca ii H&K spectral indices, respectively. We identified four subpopulations (G1, G2, G3, and G4) from CN and CH strength, with CN-weak/CH-strong G1, CN-intermediate/CH-strong G2, CN-strong/CH-intermediate G3, and CN-strong/CH-weak G4. Compared to [Na/O] from high-resolution spectroscopy, we show that CN index can more clearly separate G1 and G2. Since CN traces N abundance in a GC, it implies that G1 and G2 would show a larger difference in [N/Fe] compared to [Na/Fe], as predicted by chemical evolution models. Later generation stars G3 and G4, however, are better separated with high-resolution spectroscopy. We also found that G4 shows a stronger Ca ii H&K line strength compared to that of G1, but we suspect this to be a result of unusually strong He enhancement and/or Mg depletion in G4 of this GC. This work illustrates that combining low- and high-resolution spectroscopic studies can improve the separation of subpopulations in GCs.
- DOI
- 10.3847/1538-3881/ac0ce6
- Appears in Collections:
- 사범대학 > 과학교육과 > Journal papers
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