The first sub-70 minute non-interacting WD-BD system: EPIC212235321
journal contributionposted on 2018-02-08, 09:57 authored by S. L. Casewell, I. P. Braker, S. G. Parsons, J. J. Hermes, M. R. Burleigh, C. Belardi, A. Chaushev, N. L. Finch, M. Roy, S. P. Littlefair, M. Goad, E. Dennihy
We present the discovery of the shortest-period, non-interacting, white dwarf-brown dwarf post-common-envelope binary known. The K2 light curve shows the system, EPIC 21223532 has a period of 68.2 min and is not eclipsing, but does show a large reflection effect due to the irradiation of the brown dwarf by the white dwarf primary. Spectra show hydrogen, magnesium and calcium emission features from the brown dwarf's irradiated hemisphere, and the mass indicates the spectral type is likely to be L3. Despite having a period substantially lower than the cataclysmic variable period minimum, this system is likely a pre-cataclysmic binary, recently emerged from the common-envelope. These systems are rare, but provide limits on the lowest mass object that can survive common envelope evolution, and information about the evolution of white dwarf progenitors, and post-common envelope evolution.
S.L. Casewell acknowledges support from the University of Leicester Institute for Space and Earth Observation and I.P Braker acknowledges support from the University of Leicester College of Science and Engineering. S.G. Parsons acknowledges the support of the Leverhulme Trust. Support for this work was provided by NASA through Hubble Fellowship grant HST-HF2-51357.001-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5- 26555. This work is based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Minist´erio da Ciˆencia, Tecnologia, Inova¸c˜aos e Comunica¸c˜aoes (MCTIC) do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU). This paper also uses observations made at the South African Astronomical Observatory (SAAO). The WHT is operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias. Also based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under program ID 177.A-3011(A,B,C,D,E,F,G,H,I,J), and 099.D-0252.
CitationMonthly Notices of the Royal Astronomical Society, 2018, sty245
Author affiliation/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy
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