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\n(WDMS) binaries in the light curves of the Catalina surveys. We use a colour\nselected list of almost 2000 candidate WDMS systems from the Sloan Digital Sky\nSurvey, specifically designed to identify WDMS systems with cool white dwarfs\nand/or early M type main-sequence stars. We identify a total of 17 eclipsing\nsystems, 14 of which are new discoveries. We also find 3 candidate eclipsing\nsystems, 2 main-sequence eclipsing binaries and 22 non-eclipsing close\nbinaries. Our newly discovered systems generally have optical fluxes dominated\nby the main-sequence components, which have earlier spectral types than the\nmajority of previously discovered eclipsing systems. We find a large number of\nellipsoidally variable binaries with similar periods, near 4 hours, and\nspectral types M2--3, which are very close to Roche-lobe filling. We also find\nthat the fraction of eclipsing systems is lower than found in previous studies\nand likely reflects a lower close binary fraction among WDMS binaries with\nearly M-type main-sequence stars due to their enhanced angular momentum loss\ncompared to fully convective late M type stars, hence causing them to become\ncataclysmic variables quicker and disappear from the WDMS sample. Our systems\nbring the total number of known detached, eclipsing WDMS binaries to 71.\n