CHEMICAL INHOMOGENEITY IN RED GIANT BRANCH STARS AND RR LYRAE VARIABLES IN NGC 1851: TWO SUBPOPULATIONS IN RED GIANT BRANCH
Journal Article
·
· Astrophysical Journal (Online)
- Department of Astronomy and Space Science, Astrophysical Research Center for the Structure and Evolution of the Cosmos, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of)
- Center for Space Astrophysics and Department of Astronomy, Yonsei University, Shinchon 134, Seoul 120-749 (Korea, Republic of)
- Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764 (Korea, Republic of)
- Research School of Astronomy and Astrophysics, Australian National University, Weston, ACT 2611 (Australia)
We investigate the red giant branch (RGB) subpopulations of NGC 1851 using Ca uvby photometry. Our color-magnitude diagrams show that the RGB stars have two subpopulations and the RGB stars in NGC 1851 appear to have distinct elemental abundance patterns with the [Ca/H] abundance. We discuss that the elemental abundance patterns can be explained by the contributions from the asymptotic giant stars, confirming the previous studies by others. The RR Lyrae variables in NGC 1851 appear to have a large metallicity spread and, perhaps, a bimodal metallicity distribution. Our period shift analysis of the RR Lyrae variables shows that the helium enhancement appears to be insignificant in the NGC 1851 RR Lyrae population. However, the helium enrichment scenario in the blue or the red parts of horizontal branch (HB) cannot be completely ruled out. Our results show that about 18% of the bright RGB stars have enhanced CNO abundances, sharply in contrast to previous estimates by others ({approx}38%), making it difficult to explain the double subgiant, RGB sequences, and the bimodal HB distribution by their number ratios.
- OSTI ID:
- 21296280
- Journal Information:
- Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 1 Vol. 695; ISSN 1538-4357
- Country of Publication:
- United States
- Language:
- English
Similar Records
CYANOGEN IN NGC 1851 RED GIANT BRANCH AND ASYMPTOTIC GIANT BRANCH STARS: QUADRIMODAL DISTRIBUTIONS
THE HORIZONTAL BRANCH OF NGC 1851: CONSTRAINTS FROM ITS RR LYRAE VARIABLES
THE PRESENCE OF TWO DISTINCT RED GIANT BRANCHES IN THE GLOBULAR CLUSTER NGC 1851
Journal Article
·
Sun Dec 09 23:00:00 EST 2012
· Astrophysical Journal Letters
·
OSTI ID:22078394
THE HORIZONTAL BRANCH OF NGC 1851: CONSTRAINTS FROM ITS RR LYRAE VARIABLES
Journal Article
·
Mon Dec 31 23:00:00 EST 2012
· Astronomical Journal (New York, N.Y. Online)
·
OSTI ID:22089727
THE PRESENCE OF TWO DISTINCT RED GIANT BRANCHES IN THE GLOBULAR CLUSTER NGC 1851
Journal Article
·
Sat Dec 19 23:00:00 EST 2009
· Astrophysical Journal (Online)
·
OSTI ID:21392548