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KIC 7177553: a quadruple system of two close binaries

Lehmann, H. and Borkovits, T. and Rappaport, S. A. and Ngo, Henry and Mawet, D. and Csizmadia, Sz. and Forgács-Dajka, E. (2016) KIC 7177553: a quadruple system of two close binaries. Astrophysical Journal, 819 (1). Art. No. 33. ISSN 0004-637X. doi:10.3847/0004-637X/819/1/33.

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KIC 7177553 was observed by the Kepler satellite to be an eclipsing eccentric binary star system with an 18-day orbital period. Recently, an eclipse timing study of the Kepler binaries has revealed eclipse timing variations (ETVs) in this object with an amplitude of ~100 s and an outer period of 529 days. The implied mass of the third body is that of a super-Jupiter, but below the mass of a brown dwarf. We therefore embarked on a radial velocity (RV) study of this binary to determine its system configuration and to check the hypothesis that it hosts a giant planet. From the RV measurements, it became immediately obvious that the same Kepler target contains another eccentric binary, this one with a 16.5-day orbital period. Direct imaging using adaptive optics reveals that the two binaries are separated by 0”.4 (~167 AU) and have nearly the same magnitude (to within 2%). The close angular proximity of the two binaries and very similar γ velocities strongly suggest that KIC 7177553 is one of the rare SB4 systems consisting of two eccentric binaries where at least one system is eclipsing. Both systems consist of slowly rotating, nonevolved, solar-like stars of comparable masses. From the orbital separation and the small difference in γ velocity, we infer that the period of the outer orbit most likely lies in the range of 1000–3000 yr. New images taken over the next few years, as well as the high-precision astrometry of the Gaia satellite mission, will allow us to set much narrower constraints on the system geometry. Finally, we note that the observed ETVs in the Kepler data cannot be produced by the second binary. Further spectroscopic observations on a longer timescale will be required to prove the existence of the massive planet.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Borkovits, T.0000-0002-8806-496X
Ngo, Henry0000-0001-5172-4859
Mawet, D.0000-0002-8895-4735
Additional Information:© 2016 The American Astronomical Society. Received 2015 November 20; accepted 2016 January 10; published 2016 February 25. This work is based on observations with the 2 m Alfred Jensch Telescope of the Thüringer Landessternwarte Tautenburg. It has made use of data collected by the Kepler satellite mission, which is funded by the NASA Science Mission directorate. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work has made use of the VALD database, operated at Uppsala University, the Institute of Astronomy RAS in Moscow, and the University of Vienna. The project has been supported by the Hungarian OTKA Grant K113117.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Hungarian Scientific Research Fund (OTKA)K113117
Subject Keywords:binaries: eclipsing – binaries: spectroscopic – planetary systems – stars: fundamental parameters
Issue or Number:1
Record Number:CaltechAUTHORS:20160405-145448005
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Official Citation:H. Lehmann et al 2016 ApJ 819 33
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65942
Deposited By: Joy Painter
Deposited On:06 Apr 2016 18:16
Last Modified:10 Nov 2021 23:51

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