The connection between missing AGB stars and extended horizontal branches
arXiv:1010.5913 · doi:10.1051/0004-6361/201015405
Abstract
Recent surveys confirm early results about a deficiency or even absence of CN-strong stars on the asymptotic giant branch (AGB) of globular clusters (GCs), although with quite large cluster-to-cluster variations. In general, this is at odds with the distribution of CN band strengths among first ascent red giant branch (RGB) stars. Norris et al. proposed that the lack of CN-strong stars in some clusters is a consequence of a smaller mass of these stars that cannot evolve through the full AGB phase. In this short paper we found that the relative frequency of AGB stars can change by a factor of two between different clusters. We also find a very good correlation between the minimum mass of stars along the horizontal branch (Gratton et al. 2010) and the relative frequency of AGB stars, with a further dependence on metallicity. We conclude that indeed the stars with the smallest mass on the HB cannot evolve through the full AGB phase, being AGB-manque'. These stars likely had large He and N content, and large O-depletion. We then argue that there should not be AGB stars with extreme O depletion, and few of them with a moderate one.
5 Pages, 2 figures, A&A Accepted
References in corpus (3)
Cited by in corpus (26)
- Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
- What is a globular cluster? An observational perspective
- Mass loss on the red giant branch: the value and metallicity dependence of Reimers' η in globular clusters
- Weighing the stellar constituents of the Galactic halo with APOGEE red giant stars
- Oxygen and Sodium Abundances in M13 (NGC 6205) Giants: Linking Globular Cluster Formation Scenarios, Deep Mixing, and Post-RGB Evolution
- AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)
- Photometry and spectroscopy of multiple populations along the AGB of NGC2808 and NGC6121 (M4)
- A Chemical Composition Survey of the Iron-Complex Globular Cluster NGC 6273 (M 19)
- Multiple stellar populations of globular clusters from homogeneous Ca-Cn photometry. II. M5 (NGC 5904) and a new filter system
- Clear evidence for the presence of second-generation asymptotic giant branch stars in metal-poor Galactic globular clusters
- On the missing second generation AGB stars in NGC6752
- An extreme paucity of second population AGB stars in the normal globular cluster M4
- Why the globular cluster NGC 6752 contains no sodium-rich second-generation AGB star
- Lithium abundances in globular cluster giants: NGC 6218 (M12) and NGC 5904 (M5)
- Lost and found: evidence of Second Generation stars along the Asymptotic Giant Branch of the globular cluster NGC 6752
- Multiple stellar populations in Asymptotic Giant Branch stars of Galactic Globular Clusters
- First evidence of multiple populations along the AGB from Strömgren photometry
- Chemistry of multiple stellar populations in the mono-metallic, in situ, bulge globular cluster NGC 6388
- Slowly cooling white dwarfs in NGC 6752
- The chemical compositions of multiple stellar populations in the globular cluster NGC 2808
- AGB subpopulations in the nearby globular cluster NGC 6397
- Rare Find: Discovery and chemo-dynamical properties of two s-process enhanced RR Lyrae stars
- A Wide View of the Galactic Globular Cluster NGC 2808: Red Giant and Horizontal Branch Star Spatial Distributions
- He-enriched STAREVOL models for globular cluster multiple populations. Self-consistent isochrones from ZAMS to the TP-AGB phase
- An excess of luminous white dwarfs in the peculiar Galactic globular cluster NGC 2808
- Discovery of a hot post-AGB star in Galactic globular cluster E3