Borkovits, T, Derekas, A, Fuller, J, Szabo, GM, Pavlovski, K, Csak, B, Dozsa, A, Kovacs, J, Szabo, R, Hambleton, KM, Kinemuchi, K, Kolbas, V, Kurtz, DW, Maloney, F, Prsa, A, Southworth, J, Sztakovics, J, Biro, IB 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). 3068 - 3081.

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Abstract

KIC 8560861 (HD 183648) is a marginally eccentric (e = 0.05) eclipsing binary with an orbital period of Porb = 31.973 d, 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 M1 = 1.93 ± 0.12 M⊙, R1 = 3.30 ± 0.07 R⊙, Teff1 = 7650 ± 100 K for the primary, and M2 = 1.06 ± 0.08 M⊙, R2 = 1.11 ± 0.03 R⊙, Teff2 = 6450 ± 100 K for the secondary. After substracting 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 Pobsapse=10400±3000 y, which is ten times faster than what is theoretically expected. These findings might indicate the presence of a distant, unseen companion.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: binaries, eclipsing, stars, fundamental parameters, individual, HD 183648, oscillations
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 14 Jul 2015 13:25
Last Modified: 20 May 2019 08:11
URI: http://eprints.keele.ac.uk/id/eprint/718

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