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arXiv · 1406.4504

Ultra-short Period Binaries from the Catalina Surveys

A. J. Drake·S. G. Djorgovski·D. Garcia-Alvarez·M. J. Graham·M. Catelan·A. A. Mahabal·C. Donalek·J. L. Prieto·G. Torrealba·S. Abraham·R. Williams·S. Larson·E. Christensen
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Abstract

We investigate the properties of 367 ultra-short period binary candidates selected from 31,000 sources recently identified from Catalina Surveys data. Based on light curve morphology, along with WISE, SDSS and GALEX multi-colour photometry, we identify two distinct groups of binaries with periods below the 0.22 day contact binary minimum. In contrast to most recent work, we spectroscopically confirm the existence of M-dwarf+M-dwarf contact binary systems. By measuring the radial velocity variations for five of the shortest-period systems, we find examples of rare cool-white dwarf+M-dwarf binaries. Only a few such systems are currently known. Unlike warmer white dwarf systems, their UV flux and their optical colours and spectra are dominated by the M-dwarf companion. We contrast our discoveries with previous photometrically-selected ultra-short period contact binary candidates, and highlight the ongoing need for confirmation using spectra and associated radial velocity measurements. Overall, our analysis increases the number of ultra-short period contact binary candidates by more than an order of magnitude.

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A. J. Drake, S. G. Djorgovski, D. Garcia-Alvarez, M. J. Graham, M. Catelan, A. A. Mahabal, C. Donalek, J. L. Prieto, G. Torrealba, S. Abraham, R. Williams, S. Larson, E. Christensen. 2014-06-17. Ultra-short Period Binaries from the Catalina Surveys. https://doi.org/10.1088/0004-637x/790/2/157

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