Detection of second-generation asymptotic giant branch stars in metal-poor globular clusters

García-Hernández, D. A.
Referencia bibliográfica

Highlights on Spanish Astrophysics IX, Proceedings of the XII Scientific Meeting of the Spanish Astronomical Society held on July 18-22, 2016, in Bilbao, Spain, ISBN 978-84-606-8760-3. S. Arribas, A. Alonso-Herrero, F. Figueras, C. Hernández-Monteagudo, A. Sánchez-Lavega, S. Pérez-Hoyos (eds.), 2017 , p. 383-388

Fecha de publicación:
3
2017
Número de autores
1
Número de autores del IAC
1
Número de citas
0
Número de citas referidas
0
Descripción
Multiple stellar populations are actually known to be present in Galactic globular clusters (GCs). The first generation (FG) displays a halo-like chemical pattern, while the second generation (SG) one is enriched in Al and Na (depleted in Mg and O).Both generations of stars are found at different evolutionary stages like the main-sequence turnoff, the subgiant branch, and the red giant branch (RGB), but the SG seems to be absent - especially in metal-poor ([Fe/H] < -1) GCs - in more evolved evolutionary stages such as the asymptotic giant branch (AGB) phase. This suggests that not all SG stars experience the AGB phase and that AGB-manqué stars may be quite common in metal-poor GCs, which represents a fundamental problem for the theories of GC formation and evolution and stellar evolution. Very recently, we have combined the H-band Al abundances obtained by the APOGEE survey with ground-based optical photometry, reporting the first detection of SG Al-rich AGB stars in several metal-poor GCs with different observational properties such as horizontal branch (HB) morphology, metallicity, and age. The APOGEE observations thus resolve the apparent problem for stellar evolution, supporting the existing horizontal branch star canonical models, and may help to discern the nature of the GC polluters.