KIC 9851142: A binary star with total eclipses and ? Dor pulsations

KIC 9851142 (V2094 Cyg, HD 188854) is an eccentric eclipsing binary with an orbital period of Porb=8.4854 d, exhibiting millimagnitude (mmag) amplitude pulsations on time scales of a few days. I present the results of the analysis of high-resolution spectroscopic data and Kepler long and short cadence photometry. The iterative combination of spectral classification by atmospheric analysis, radial velocity and eclipse timing variation studies, separation of pulsational features of the light curve, and binary light curve analysis led to the accurate determination of the fundamental stellar parameters and the comparison with evolutionary models strict constraints on the system age. I found that the binary is composed of two main sequence stars with an age of 0.75 ± 0.21 Gyr, having masses, radii and temperatures of M1 = 1.79 ± 0.11 M?, R1 = 2.47 ± 0.07 R?, Teff1 = 7250 ± 480 K for the primary, and M2 = 0.83 ± 0.12 M?, R2 = 0.67 ± 0.05 R?, Teff2 = 5050 ± 650 K for the secondary. Multiple frequency analyses techniques were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of KIC 9851142 is a ? Dor type pulsating star, exhibiting five pulsation frequencies in the range of 0.6-1.95 d-1 with amplitudes of 0.29-6.72 mmag and pulsation constants of 0.24-0.27 d. The analysis of the eclipse timing variations revealed preliminary apsidal motion with a period of Pobs apse = 240 ± 29 y. Only six eclipsing binaries have been known to contain ? Dor pulsating components and, therefore, KIC 9851142 will be an important test-bed for examining these exceptional and interesting objects. © 2015 Elsevier B.V. All rights reserved.Ministero dell’Istruzione, dell’Università e della Ricerca, MIUR 114F354 Ministero dell’Istruzione, dell’Università e della Ricerca, MIURThis work was partially supported by the Italian Ministero dell’Istruzione, Università e Ricerca (MIUR). The following internet-based resources were used in research for this paper: the NASA Astrophysics Data System; the SIMBAD database operated at CDS, Strasbourg, France; and the ar ? iv scientific paper preprint service operated by Cornell University. I warmly thank the referee for the many suggestions that made this work more readable and formally correct. This study is supported by Turkish Scientific and Technology Council under project number 114F354. -