14 new eclipsing white dwarf plus main-sequence binaries from the SDSS and Catalina surveys

Abstract

We report on the search for new eclipsing white dwarf plus main-sequence (WDMS) binaries in the light curves of the Catalina surveys. We use a colour-selected list of almost 2000 candidate WDMS systems from the Sloan Digital Sky Survey, specifically designed to identify WDMS systems with cool white dwarfs and/or early M-type main-sequence stars. We identify a total of 17 eclipsing systems, 14 of which are new discoveries. We also find three candidate eclipsing systems, two main-sequence eclipsing binaries and 22 non-eclipsing close binaries. Our newly discovered systems generally have optical fluxes dominated by the main-sequence components, which have earlier spectral types than the majority of previously discovered eclipsing systems. We find a large number of ellipsoidally variable binaries with similar periods, near 4 h, and spectral types M2–3, which are very close to Roche lobe filling. We also find that the fraction of eclipsing systems is lower than found in previous studies and likely reflects a lower close binary fraction among WDMS binaries with early M-type main-sequence stars due to their enhanced angular momentum loss compared to fully convective late M-type stars, hence causing them to become cataclysmic variables quicker and disappear from the WDMS sample. Our systems bring the total number of known detached, eclipsing WDMS binaries to 71.

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© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 February 18. Received 2015 February 17; in original form 2015 February 2. First published online March 30, 2015. We thank the referee for useful comments and suggestions. SGP acknowledges financial support from FONDECYT in the form of grant number 3140585. ULTRACAM, VSD and SPL are supported by the Science and Technology Facilities Council (STFC). TRM and EB were supported the STFC #ST/L000733/1. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 320964 (WDTracer). MRS thanks for support from FONDECYT(1141269) and Millennium Science Initiative, Chilean ministry of Economy: Nucleus RC130007. ARM acknowledges financial support from the Postdoctoral Science Foundation of China (grants 2013M530470 and 2014T70010) and from the Research Fund for International Young Scientists by the National Natural Science Foundation of China (grant 11350110496). We also acknowledge the travel support provided by the Royal Society. This work has made use of data obtained at the Thai National Observatory on Doi Inthanon, operated by NARIT.

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Submitted - 1502.05723v1.pdf

Published - MNRAS-2015-Parsons-2194-204.pdf

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