2015MNRAS.447..680G -
Mon. Not. R. Astron. Soc., 447, 680-690 (2015/February-2)
Asteroseismic analysis of two α-enhanced stars KIC 7976303 and KIC 8694723.
GE Z.S., BI S.L., LI T.D., LIU K., TIAN Z.J., YANG W.M., LIU Z.E. and YU J.
Abstract (from CDS):
We intend to use stellar models with and without α-enhancement, as well as asteroseismic analysis, to study two α-enhanced stars, KIC 7976303 and KIC 8694723. For the α-enhanced models, we adopt [α/Fe] = 0.2 and 0.4. For the evolved subgiant KIC 7976303 with mixed modes, the α-enhanced models fit the observations better than the models without α-enhancement, and point to a star with M = 1.20±0.02M☉, t = 4.88±0.08Gyr, R = 2.04±0.01 R☉ and L = 5.07±0.05 L☉. For the post turn-off star KIC 8694723, we find that the models fit the observations well in all three cases ([α/Fe] = 0.0, 0.2 and 0.4). According to the observed metal abundances, only α-enhanced models are used to estimate the stellar parameters, which are M = 1.13±0.06M☉, t = 5.47±0.43Gyr, R = 1.55±0.13 R☉ and L = 3.18±0.26 L☉. Our α-enhanced models indicate that KIC 7976303 has a larger mass and younger age than in previous works based on standard models. Furthermore, the differences of estimated mass and age between the three cases are ∼ 0.1M☉ and ∼ 0.5-1.3Gyr. These results suggest that we include α-enhancement in the modelling of α-enhanced stars, such as members of globular clusters and metal-poor stars in the disc and in the halo.
Abstract Copyright:
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
Journal keyword(s):
stars: abundances - stars: evolution - stars: oscillations - stars: solar-type
Simbad objects:
2
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