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Kepler Eclipsing Binaries with Delta Scuti/Gamma Doradus Pulsating Components I: KIC 9851944

Z. Guo, D. R. Gies, R. A. Matson, A. GarcŪa HernŠndez

Abstract
KIC 9851944 is a short-period (P = 2.16 days) eclipsing binary in the Kepler field of view. By combining the analysis of Kepler photometry and phase-resolved spectra from Kitt Peak National Observatory and Lowell Observatory, we determine the atmospheric and physical parameters of both stars. The two components have very different radii (2.27 R, 3.19 R) but close masses (1.76 M, 1.79 M) and effective temperatures (7026, 6902 K), indicating different evolutionary stages. The hotter primary is still on the main sequence (MS), while the cooler and larger secondary star has evolved to the post-MS, burning hydrogen in a shell. A comparison with coeval evolutionary models shows that it requires solar metallicity and a higher mass ratio to fit the radii and temperatures of both stars simultaneously. Both components show δ Scuti-type pulsations, which we interpret as p-modes and p and g mixed modes. After a close examination of the evolution of δ Scuti pulsational frequencies, we make a comparison of the observed frequencies with those calculated from MESA/GYRE.

Keywords
binaries: eclipsing, binaries: spectroscopic, stars: individual: KIC 9851944, stars: oscillations

The Astrophysical Journal
Volume 826, Number 1
2016 July

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Instituto de Astrof√≠sica e Ci√™ncias do Espa√ßo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia