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HD 183648: a Kepler eclipsing binary with anomalous ellipsoidal variations and a pulsating component

Borkovits, T. and Derekas, A. and Fuller, J. and Szabo, G. M. and Pavlovski, K. and Csak, B. and Dozsa, A. and Kovacs, J. and Szabo, R. and Hambleton, K. M. and Kinemuchi, K. and Kolbas, V. and Kurtz, D. W. and Maloney, F. and Prsa, A. and Southworth, J. and Sztakovics, J. and Biro, I. B. and Jankovics, I. (2014) HD 183648: a Kepler eclipsing binary with anomalous ellipsoidal variations and a pulsating component. Monthly Notices of the Royal Astronomical Society, 443 (4). pp. 3068-3081. ISSN 0035-8711

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Abstract

KIC 8560861 (HD 183648) is a marginally eccentric (e=0.05) eclipsing binary with an orbital period of P_orb=31.973d, exhibiting mmag amplitude pulsations on time scales of a few days. We present the results of the complex analysis of high and medium-resolution spectroscopic data and Kepler Q0 -- Q16 long cadence photometry. The iterative combination of spectral disentangling, 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. We found that the binary is composed of two main sequence stars with an age of 0.9\+-0.2 Gyr, having masses, radii and temperatures of M_1=1.93+-0.12 M_sun, R_1=3.30+-0.07 R_sun, T_eff1=7650+-100 K for the primary, and M_2=1.06+-0.08 M_sun, R_2=1.11+-0.03 R_sun, T_eff2=6450+-100 K for the secondary. After subtracting the binary model, we found three independent frequencies, two of which are separated by twice the orbital frequency. We also found an enigmatic half orbital period sinusoidal variation that we attribute to an anomalous ellipsoidal effect. Both of these observations indicate that tidal effects are strongly influencing the luminosity variations of HD 183648. The analysis of the eclipse timing variations revealed both a parabolic trend, and apsidal motion with a period of (P_apse)_obs=10,400+-3,000 y, which is three times faster than what is theoretically expected. These findings might indicate the presence of a distant, unseen companion.

Item Type: Article
Subjects: Q Science / természettudomány > QB Astronomy, Astrophysics / csillagászat, asztrofizika
Depositing User: Dr Szabó M. Gyula
Date Deposited: 18 Sep 2014 13:32
Last Modified: 18 Sep 2014 13:32
URI: http://real.mtak.hu/id/eprint/15424

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