Burgasser, Adam J. and Kirkpatrick, J. Davy and Brown, Michael E. and Reid, I. Neill and Gizis, John E. and Dahn, Conard C. and Monet, David G. and Beichman, Charles A. and Liebert, James and Cutri, Roc M. and Skrutskie, Michael F. (1999) Discovery of Four Field Methane (T-Type) Dwarfs with the Two Micron All-Sky Survey. Astrophysical Journal Letters, 522 (1). L65-L68. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120928-140004107
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We report the discovery of four field methane ("T"-type) brown dwarfs using Two Micron All-Sky Survey (2MASS) data. One additional methane dwarf, previously discovered by the Sloan Digital Sky Survey, was also identified. Near-infrared spectra clearly show the 1.6 and 2.2 μm CH_4 absorption bands characteristic of objects with T_(eff) ≾ 1300 K as well as broadened H_2O bands at 1.4 and 1.9 μm. Comparing the spectra of these objects with that of Gl 229B, we propose that all new 2MASS T dwarfs are warmer than 950 K, in order from warmest to coolest: 2MASS J1217-03, 2MASS J1225-27, 2MASS J1047+21, and 2MASS J1237+65. Based on this preliminary sample, we find a warm T dwarf surface density of 0.0022 T dwarfs deg^(-2), or ~90 warm T dwarfs over the whole sky detectable to J < 16. The resulting space density upper limit, 0.01 T dwarfs pc^(-3), is comparable to that of the first L dwarf sample from Kirkpatrick et al.
|Additional Information:||© 1999 American Astronomical Society. Received 1999 June 10; accepted 1999 July 1; published 1999 August 3. A. J. B. would like to thank Tom Geballe and Sandy Leggett for the use of their recalibrated Gl 229B UKIRT spectrum, Ben Oppenheimer for his valuable comments, Albert Burgasser for consultation on a T dwarf search database, and especially the 2MASS staff and scientists for their support and for pointing their telescopes in the right directions. J. D. K. acknowledges Michael Strauss, Jill Knapp, and Xiaohui Fan for sharing news of their T dwarf discovery prior to publication. A. J. B., J. D. K., I. N. R., and J. L. acknowledge funding through a NASA/JPL grant to 2MASS Core Project science. A. J. B., J. D. K., R. M. C., and C. A. B. acknowledge the support of the Jet Propulsion Laboratory, California Institute of Technology, which is operated under contract with the National Aeronautics and Space Administration. 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, funded by the National Aeronautics and Space Administration and the National Science Foundation.|
|Subject Keywords:||infrared: stars; stars: fundamental parameters; stars: individual (2MASSI J1047539+212423, 2MASSW J1217111–031113, 2MASSW J1225543–273947, 2MASSW J1237392+652615, 2MASSW J1346464–003150); stars: low-mass, brown dwarfs|
|Official Citation:||Discovery of Four Field Methane (T-Type) Dwarfs with the Two Micron All-Sky Survey Adam J. Burgasser et al. 1999 ApJ 522 L65|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||28 Sep 2012 21:18|
|Last Modified:||27 Dec 2012 02:46|
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