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

Borkovits, T.; Derekas, A.; Fuller, J.; Szabó, Gy.M.; Pavlovski, K.; Csák, B.; Dózsa, Á.; Kovács, J.; Szabó, R.; Hambleton, K.M.; Kinemuchi, K.; Kolbas, V.; Kurtz, D.W.; Maloney, F.; Prša, A.; Southworth, J.; Sztakovics, J.; Bíró, I.B.; Jankovics, I.

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


Authors

T. Borkovits

A. Derekas

J. Fuller

Gy.M. Szabó

K. Pavlovski

B. Csák

Á. Dózsa

J. Kovács

R. Szabó

K.M. Hambleton

K. Kinemuchi

V. Kolbas

D.W. Kurtz

F. Maloney

A. Prša

J. Sztakovics

I.B. Bíró

I. Jankovics



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.

Citation

Borkovits, T., Derekas, A., Fuller, J., Szabó, G., Pavlovski, K., Csák, B., …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. https://doi.org/10.1093/mnras/stu1379

Journal Article Type Article
Acceptance Date Jul 6, 2014
Online Publication Date Aug 6, 2014
Publication Date Oct 1, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 443
Issue 4
Pages 3068 - 3081
DOI https://doi.org/10.1093/mnras/stu1379
Keywords binaries, eclipsing, stars, fundamental parameters, individual, HD 183648, oscillations
Publisher URL http://dx.doi.org/10.1093/mnras/stu1379

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