Bibcode
Mathur, S.; García, R. A.; Huber, D.; Regulo, C.; Stello, D.; Beck, P. G.; Houmani, K.; Salabert, D.
Referencia bibliográfica
The Astrophysical Journal, Volume 827, Issue 1, article id. 50, 12 pp. (2016).
Fecha de publicación:
8
2016
Revista
Número de citas
44
Número de citas referidas
37
Descripción
Asteroseismology has proven to be an excellent tool to determine not
only global stellar properties with good precision, but also to infer
the stellar structure, dynamics, and evolution for a large sample of
Kepler stars. Prior to the launch of the mission, the properties of
Kepler targets were inferred from broadband photometry, leading to the
Kepler Input Catalog (KIC). The KIC was later revised in the Kepler Star
Properties Catalog, based on literature values and an asteroseismic
analysis of stars that were unclassified in the KIC. Here, we present an
asteroseismic analysis of 45,400 stars that were classified as dwarfs in
the Kepler Star Properties Catalog. We found that around 2% of the
sample shows acoustic modes in the typical frequency range that put them
in the red-giant category rather than the cool dwarf category. We
analyze the asteroseismic properties of these stars, derive their
surface gravities, masses, and radii, and present updated effective
temperatures and distances. We show that the sample is significantly
fainter than the previously known oscillating giants in the Kepler
field, with the faintest stars reaching down to a Kepler magnitude of Kp
˜ 16. We demonstrate that 404 stars are at distances beyond 5 kpc
and that the stars are significantly less massive than for the original
Kepler red-giant sample, consistent with a population of distant halo
giants. A comparison with a galactic population model shows that up to
40 stars might be genuine halo giants, which would increase the number
of known asteroseismic halo stars by a factor of 4. The detections
presented here will provide a valuable sample for galactic archeology
studies.