Asteroseismology of red-clump stars with CoRoT and Kepler
Miglio, Andrea[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie]
Montalban Iglesias, Josefa[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie]
Eggenberger, P.[Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland]
Hekker, S.[School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT United Kingdom; Instituut voor Sterrenkunde, K. U. Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium]
Noels-Grötsch, Arlette[Institut d'Astrophysique et de Géophysique de l'Université de Liège, Allée du 6 Août, 17 B-4000 Liège, Belgium]
[en] Pulsations ; oscillations ; and stellar seismology ; Cepheids ; Giant and subgiant stars
[en] The availability of asteroseismic constraints for a large number of red giants with CoRoT and, in the near future with Kepler, paves the way for detailed studies of populations of galactic-disk red giants. We investigate which information on the observed population can be recovered by the distribution of the observed seismic constraints: the frequency of maximum power of solar-like oscillations (νmax) and the large frequency separation (Δν). We use the distribution of νmax and of Δν observed by CoRoT in nearly 800 red giants in the first long observational run, as a tool to investigate the properties of galactic red-giant stars through the comparison with simulated distributions based on synthetic stellar populations. We can clearly identify the bulk of the red giants observed by CoRoT as red-clump stars, i.e. post-flash core-He-burning stars. The distribution of νmax and of Δν give us access to the distribution of the stellar radius and mass, and thus represent a most promising probe of the age and star formation rate of the disk, and of the mass-loss rate during the red-giant branch. This approach will be of great utility also in the interpretation of forthcoming surveys of variability of red giants with CoRoT and Kepler. In particular, an asteroseismic mass estimate of clump stars in the old-open clusters observed by Kepler, would represent a most valuable observational test of the poorly known mass-loss rate on the giant branch, and of its dependence on metallicity.