The Close Binary Fraction of Dwarf M Stars
Abstract
We describe a search for close spectroscopic dwarf M star binaries using data from the Sloan Digital Sky Survey to address the question of the rate of occurrence of multiplicity in M dwarfs. We use a template-fitting technique to measure radial velocities from 145,888 individual spectra obtained for a magnitude-limited sample of 39,543 M dwarfs. Typically, the three or four spectra observed for each star are separated in time by less than four hours, but for ~17% of the stars, the individual observations span more than two days. In these cases we are sensitive to large-amplitude radial velocity variations on timescales comparable to the separation between the observations. We use a control sample of objects having observations taken within a four-hour period to make an empirical estimate of the underlying radial velocity error distribution and simulate our detection efficiency for a wide range of binary star systems. We find the frequency of binaries among the dwarf M stars with a < 0.4 AU to be 3%-4%. Comparison with other samples of binary stars demonstrates that the close binary fraction, like the total binary fraction, is an increasing function of primary mass.
Additional Information
© 2012 American Astronomical Society. Received 2011 July 28; accepted 2011 October 16; published 2011 December 20. The authors thank an anonymous referee for helpful comments that helped to improve this manuscript. We also thank Jim Gunn, Craig Loomis, Steve Bickerton, Fergal Mullally, and Robert Lupton for their extensive work on the SDSS spectroscopic pipeline and in particular for making available the calibrated individual 15 minute spectra. We also thank David Latham for helpful conversations that contributed to this work. C.H.B. thanks the National Science Foundation for support via NSF postdoctoral fellowship AST-0901918, and G.R.K. thanks the NSF and NASA for support via grants NNX07AH68G and AST-0706938. We thank Princeton's astrophysics department, in particular David Spergel, for strong support of the undergraduate research program, which supported this work. Funding for SDSS and for SDSS-II was provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions.Attached Files
Published - Clark2012p16942Astrophys_J.pdf
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Additional details
- Eprint ID
- 29071
- Resolver ID
- CaltechAUTHORS:20120201-141223904
- AST-0901918
- NSF Postdoctoral Fellowship
- AST-0706938
- NSF
- NNX07AH68G
- NASA
- Created
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2012-02-01Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field