Looper, Dagny L. and Kirkpatrick, J. Davy and Burgasser, Adam J. (2007) Discovery of 11 new T dwarfs in the two micron all sky survey, including a possible L/T transition binary. Astronomical Journal, 134 (3). pp. 1162-1182. ISSN 0004-6256 http://resolver.caltech.edu/CaltechAUTHORS:LOOaj07
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We present the discovery of 11 new T dwarfs, found during the course of a photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog and from a proper-motion-selected sample of ultracool dwarfs in the 2MASS Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph, we obtained low-resolution (R ~ 150) spectroscopy, allowing us to derive near-infrared spectral types of T2-T8. We also present improved signal-to-noise ratio SpeX low-resolution spectroscopy of the near-infrared T0 standard SDSS J120747.17+024424.8 and T1 standard SDSSp J083717.22-000018.3. One of these new T dwarfs, 2MASS J13243559+6358284, was also discovered independently by Metchev et al. This object is spectroscopically peculiar and possibly a binary and/or very young (<300 Myr). We specifically attempted to model the spectrum of this source as a composite binary to reproduce its peculiar spectral characteristics. The latest type object in our sample is a T8 dwarf, 2MASS J07290002-3954043, now one of the four latest type T dwarfs known. All 11 T dwarfs are nearby given their spectrophotometric distance estimates, with one T dwarf within 10 pc and eight additional T dwarfs within 25 pc, if single. These new additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers an excellent opportunity to probe for companions at separations closer than are possible for more distant T dwarfs.
|Additional Information:||© 2007 The American Astronomical Society. Received 2007 March 28; accepted 2007 May 30. D. L. L. thanks J. Rayner for advising her for part of this project and for a careful read of the manuscript.We would like to thank J. Kartaltepe and Y. Kakazu for imaging several of our targets with the UH 2.2 m ULBCAM and for teaching D. L. L. how to use the instrument. We thank S. Metchev for helping us with the SDSS Catalog, Mike Cushing for useful discussions, and Kevin Luhman for kindly providing the spectrum of HN Peg B.We would also like to thank our telescope operators on IRTF: D. Griep and B. Golisch. This paper uses data from the IRTF Spectral Library (http://irtfweb.ifa.hawaii.edu/spex/spexlibrary/ IRTFlibrary.html ) and from http://DwarfArchives.org. This publication also makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/ California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. D. L. L. was a guest user of the Canadian Astronomy Data Centre, which is operated by the Herzberg Institute of Astrophysics, National Research Council of Canada. This research has also made use of the NASA/ IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the NationalAeronautics and SpaceAdministration. As all spectroscopic and imaging follow-up data were obtained from the summit of Mauna Kea, the authors wish to recognize and acknowledge the very significant cultural role and reverence that this mountaintop has always had within the indigenous Hawaiian community.We are most fortunate to have the opportunity to conduct observations on the summit.|
|Subject Keywords:||stars: low-mass, brown dwarfs; techniques: spectroscopic|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||24 Jun 2009 22:49|
|Last Modified:||26 Dec 2012 10:53|
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