CoRoT Symposium 3, Kepler KASC-7 joint meeting
6-11 Jul 2014 Toulouse (France)

Abstracts > Derekas A.

HD183648: a Kepler eclipsing binary with anomalous ellipsoidal variations and a pulsating component
A. Derekas  1, 2, *@  , T. Borkovits  1, 2, 3@  , J. Fuller  4  , Gy. Szabo  1, 2  , K. Pavlovski  5  , B. Csak  2  , A. Dozsa  2  , J. Kovacs  2  , R. Szabo  1  , K. Hambleton  6, 7  , K. Kinemuchi  8  , V. Kolbas  5  , D. Kurtz  6  , F. Maloney  7  , A. Prsa  7  , J. Southworth  9  , J. Sztakovics  10  , I. Biro  3  , I. Jankovics  2  
1 : Konkoly Observatory, MTA CSFK
H-1121 Budapest, Konkoly Thege M. ut 15-17 -  Hungary
2 : ELTE Gothard Astrophysical Observatory
H-9704 Szombathely, Szent Imre herceg ut 112 -  Hungary
3 : Baja Astronomical Observatory
H-6500 Baja, Szegedi ut, Kt. 766 -  Hungary
4 : Department of Astronomy, Center for Space Research, Cornell University
Ithaca, NY 14853 -  United States
5 : Department of Physics, University of Zagreb
Bijenicka cesta 32, 10000 Zagreb -  Croatia
6 : Jeremiah Horrocks Institute, University of Central Lancashire
Preston PR1 2HE -  United Kingdom
7 : Department of Astrophysics and Planetary Science, Villanova University
800 Lancaster Ave, Villanova PA 19085 -  United States
8 : Apache Point Observatory
Sunspot NM 88349 -  United States
9 : Astrophysics Group, Keele University
Newcastle-under-Lyme, ST5 5BG -  United Kingdom
10 : Astronomical Department of Eotvos University
H-1118 Pazmany Peter stny. 1/A, Budapest -  Hungary
* : Corresponding author

HD183648 (KIC8560861) is a slightly eccentric (e = 0.05) eclipsing binary system with an orbital period of 31.973 days, 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 of the highest signal-to-noise ratio averaged spectra, 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 masses of 1.93 and 1.06 solar masses. After substracting the binary model from the observed light curve, 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 with an opposite phase than usually observed. Both of these observations indicate that tidal effects are strongly influencing the luminosity variations of HD183648. The analysis of the eclipse timing variations revealed both a parabolic trend suggesting constant period variation, and apsidal motion. The parabolic eclipse timing variations and the apsidal motion discrepancy might be indicators of the presence of a distant, unseen third companion in the system.

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