Burgasser, Adam J. and Cruz, Kelle L. and Cushing, Michael and Gelino, Christopher R. and Looper, Dagny L. and Faherty, Jacqueline K. and Kirkpatrick, J. Davy and Reid, I. Neill (2010) SpeX Spectroscopy of Unresolved Very Low Mass Binaries. I. Identification of 17 Candidate Binaries Straddling the L Dwarf/T Dwarf Transition. Astrophysical Journal, 710 (2). pp. 1142-1169. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100304-111258728
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We report the identification of 17 candidate brown dwarf binaries whose components straddle the L dwarf/T dwarf transition. These sources were culled from a large near-infrared spectral sample of L and T dwarfs observed with the Infrared Telescope Facility SpeX spectrograph. Candidates were selected on the basis of spectral ratios which segregate known (resolved) L dwarf/T dwarf pairs from presumably single sources. Composite templates, constructed by combining 13,581 pairs of absolute flux-calibrated spectra, are shown to provide statistically superior fits to the spectra of our 17 candidates as compared to single templates. Ten of these candidates appear to have secondary components that are significantly brighter than their primaries over the 1.0-1.3 μm band, indicative of rapid condensate depletion at the L dwarf/T dwarf transition. Our results support prior indications of enhanced multiplicity amongst early-type T dwarfs; 53% ± 7% of the T0-T4 dwarfs in our spectral sample are found to be either resolved or unresolved (candidate) pairs, although this is consistent with an intrinsic (volume complete) brown dwarf binary fraction of only 15%. If verified, this sample of spectral binaries more than doubles the number of known L dwarf/T dwarf transition pairs, enabling a broader exploration of this poorly understood phase of brown dwarf atmospheric evolution.
|Additional Information:||© 2010 The American Astronomical Society. Received 2009 June 16; accepted 2010 January 5; published 2010 January 27. The authors thank telescope operators Bill Golisch, Dave Griep, and Paul Sears, and instrument specialist John Rayner, for their assistance during our many IRTF runs. The authors also thank the anonymous referee for her/his review of the manuscript. This publication makes use of data from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, and funded by the National Aeronautics and Space Administration and the National Science Foundation. 2MASS data were obtained from the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This research has also made use of the SIMBAD database, operated at CDS, Strasbourg, France; the M, L, and T dwarf compendium housed at DwarfArchives.org and maintained by Chris Gelino, Davy Kirkpatrick, and Adam Burgasser; the SpeX Prism Spectral Libraries, maintained by Adam Burgasser at http://www.browndwarfs.org/spexprism; and the VLM Binaries Archive maintained by Nick Siegler at http://www.vlmbinaries.org. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: IRTF (SpeX)|
|Subject Keywords:||binaries: general; brown dwarfs; stars: fundamental parameters; stars: low-mass|
|Official Citation:||SpeX Spectroscopy of Unresolved Very Low Mass Binaries. I. Identification of 17 Candidate Binaries Straddling the L Dwarf/T Dwarf Transition Adam J. Burgasser, Kelle L. Cruz, Michael Cushing, Christopher R. Gelino, Dagny L. Looper, Jacqueline K. Faherty, J. Davy Kirkpatrick, and I. Neill Reid 2010 ApJ 710 1142-1169 doi: 10.1088/0004-637X/710/2/1142|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||12 Mar 2010 19:20|
|Last Modified:||26 Dec 2012 11:49|
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