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The Full Kepler Phase Curve of the Eclipsing Hot White Dwarf Binary System KOI-964

Wong, Ian and Shporer, Avi and Becker, Juliette C. and Fulton, Benjamin J. and Berger, Travis A. and Weinberg, Nevin N. and Arras, Phil and Howard, Andrew W. and Benneke, Björn (2020) The Full Kepler Phase Curve of the Eclipsing Hot White Dwarf Binary System KOI-964. Astronomical Journal, 159 (1). Art. No. 29. ISSN 1538-3881. https://resolver.caltech.edu/CaltechAUTHORS:20191120-110538435

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Abstract

We analyze the full Kepler phase curve of KOI-964, a binary system consisting of a hot white dwarf on an eclipsing orbit around an A-type host star. Using all 18 quarters of long-cadence photometry, we carry out a joint light-curve fit and obtain improved phase-curve amplitudes, occultation depths, orbital parameters, and transit ephemeris over the previous results of Carter et al. A periodogram of the residuals from the phase-curve fit reveals an additional stellar variability signal from the host star with a characteristic period of 0.620276 ± 0.000011 days and a full amplitude of 24 ± 2 ppm. We also present new Keck/HIRES radial velocity observations, which we use to measure the orbit and obtain a mass ratio of q = 0.106 ± 0.012. Combining this measurement with the results of a stellar isochrone analysis, we find that the masses of the host star and white dwarf companion are 2.23 ± 0.12 M⊙ and 0.236^(+0.028)_(−0.027) M⊙, respectively. The effective temperatures of the two components are 9940^(+260)_(−230) K and 15,080 ± 400 K, respectively, and we determine the age of the system to be 0.21^(+0.11)_(−0.08) Gyr. We use the measured system properties to compute predicted phase-curve amplitudes and find that while the measured Doppler-boosting and mutual illumination components agree well with theory, the ellipsoidal distortion amplitude is significantly underestimated. We detail possible explanations for this discrepancy, including interactions between the dynamical tide of the host star and the tidal bulge and possible nonsynchronous rotation of the host star.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-3881/ab59d6DOIArticle
https://arxiv.org/abs/1910.08524arXivDiscussion Paper
ORCID:
AuthorORCID
Wong, Ian0000-0001-9665-8429
Shporer, Avi0000-0002-1836-3120
Becker, Juliette C.0000-0002-7733-4522
Fulton, Benjamin J.0000-0003-3504-5316
Berger, Travis A.0000-0002-2580-3614
Weinberg, Nevin N.0000-0001-9194-2084
Howard, Andrew W.0000-0001-8638-0320
Benneke, Björn0000-0001-5578-1498
Additional Information:© 2019 The American Astronomical Society. Received 2019 October 18; revised 2019 November 19; accepted 2019 November 19; published 2019 December 23. This work includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. We thank the California Planet Survey observers who helped to collect the Keck/HIRES data. 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. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. I.W. and J.C.B. are supported by Heising-Simons 51 Pegasi b postdoctoral fellowships.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NASAUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Heising-Simons Foundation51 Pegasi b Fellowship
Subject Keywords:Eclipsing binary stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Eclipsing binary stars (444)
Record Number:CaltechAUTHORS:20191120-110538435
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191120-110538435
Official Citation:Ian Wong et al 2020 AJ 159 29
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99955
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:20 Nov 2019 19:26
Last Modified:23 Dec 2019 18:30

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