F. Baudin, C. Barban, M. J. Goupil, R. Samadi, Y. Lebreton, H. Bruntt, T. Morel, L. Lefèvre, E. Michel, B. Mosser, F. Carrier, J. De Ridder, A. Hatzes, S. Hekker, T. Kallinger, M. Auvergne, A. Baglin, C. Catala
The G6 giant HR\,2582 (HD\,50890) was observed by CoRoT for approximately 55
days. Mode frequencies are extracted from the observed Fourier spectrum of the
light curve. Numerical stellar models are then computed to determine the
characteristics of the star (mass, age, etc...) from the comparison with
observational constraints. We provide evidence for the presence of solar-like
oscillations at low frequency, between 10 and 20\,$\mu$Hz, with a regular
spacing of $(1.7\pm0.1)\mu$Hz between consecutive radial orders. Only radial
modes are clearly visible. From the models compatible with the observational
constraints used here, We find that HR\,2582 (HD\,50890) is a massive star with
a mass in the range (3--\,5\,$M_{\odot}$), clearly above the red clump. It
oscillates with rather low radial order ($n$ = 5\,--\,12) modes. Its
evolutionary stage cannot be determined with precision: the star could be on
the ascending red giant branch (hydrogen shell burning) with an age of
approximately 155 Myr or in a later phase (helium burning). In order to obtain
a reasonable helium amount, the metallicity of the star must be quite subsolar.
Our best models are obtained with a mixing length significantly smaller than
that obtained for the Sun with the same physical description (except
overshoot). The amount of core overshoot during the main-sequence phase is
found to be mild, of the order of 0.1\,$H_{\rm p}$.
View original:
http://arxiv.org/abs/1111.6543
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