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Published December 1, 2016 | Published + Accepted Version
Journal Article Open

KIC 3749404: a heartbeat star with rapid apsidal advance indicative of a tertiary component


Heartbeat stars are eccentric (e > 0.2) ellipsoidal variables whose light curves resemble a cardiogram. We present the observations and corresponding model of KIC 3749404, a highly eccentric (e = 0.66), short period (P = 20.3 d) heartbeat star with tidally induced pulsations. A binary star model was created using PHOEBE, which we modified to include tidally induced pulsations and Doppler boosting. The morphology of the photometric periastron variation (heartbeat) depends strongly on the eccentricity, inclination and argument of periastron. We show that the inclusion of tidally induced pulsations in the model significantly changes the parameter values, specifically the inclination and those parameters dependent on it. Furthermore, we determine the rate of apsidal advance by modelling the periastron variation at the beginning and end of the 4-yr Kepler data set and dividing by the elapsed time. We compare the model with the theoretical expectations for classical and general relativistic apsidal motion and find the observed rate to be two orders of magnitude greater than the theoretical rate. We find that the observed rate cannot be explained by tidally induced pulsations alone and consequently hypothesize the presence of a third body in the system.

Additional Information

© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 August 4. Received 2016 August 4; in original form 2016 May 26. The authors express their sincere thanks to NASA and the Kepler team for allowing them to work with and analyse the Kepler data making this work possible. The Kepler mission is funded by NASA's Science Mission Directorate. KH and AP acknowledge support from the NSF grant #1517460. This work was also supported by the STFC (Science and Technology Funding Council). The authors would like to thank Ed Guinan for the enlightening discussion on apsidal motion. KH, ST and JF acknowledge support through NASA K2 GO grant (11-KEPLER11-0056). We would like to thank the RAS for providing grants which enabled KH's attendance to conferences and thus enabled the development of collaborations and the successful completion of this work. AP acknowledges support through NASA K2 GO grant (NASA 14-K2GO1_2-0057). For the spectroscopic observations and results from TRES, DWL and SNQ acknowledge partial support from the Kepler mission under NASA Cooperative Agreement NNX11AB99A to the Smithsonian Astrophysical Observatory. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

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Accepted Version - 1608.02493


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