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arXiv · 1104.2537

FIRE Spectroscopy of Five Late-type T Dwarfs Discovered with the Wide-field Infrared Survey Explorer

Adam J. Burgasser·Michael C. Cushing·J. Davy Kirkpatrick·Christopher R. Gelino·Roger L. Griffith·Dagny L. Looper·Christopher Tinney·Robert A. Simcoe·John J. Bochanski·Michael F. Skrutskie·A. Mainzer·Maggie A. Thompson·Kenneth A. Marsh·James M. Bauer·Edward L. Wright
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Abstract

We present the discovery of five late-type T dwarfs identified with the Wide-field Infrared Survey Explorer (WISE). Low-resolution near-infrared spectroscopy obtained with the Magellan Folded-port InfraRed Echellette (FIRE) reveal strong water and methane absorption in all five sources, and spectral indices and comparison to spectral templates indicate classifications ranging from T5.5 to T8.5:. The spectrum of the latest-type source, WISE J1812+2721, is an excellent match to that of the T8.5 companion brown dwarf Wolf 940B. WISE-based spectrophotometric distance estimates place these T dwarfs at 12-13 pc from the Sun, assuming they are single. Preliminary fits of the spectral data to the atmosphere models of Saumon & Marley indicate effective temperatures ranging from 600 K to 930 K, both cloudy and cloud-free atmospheres, and a broad range of ages and masses. In particular, two sources show evidence of both low surface gravity and cloudy atmospheres, tentatively supporting a trend noted in other young brown dwarfs and exoplanets. In contrast, the high proper motion T dwarf WISE J2018-7423 exhibits a suppressed K-band peak and blue spectrophotometric J-K colors indicative of an old, massive brown dwarf; however, it lacks the broadened Y-band peak seen in metal-poor counterparts. These results illustrate the broad diversity of low-temperature brown dwarfs that will be uncovered with WISE.

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Adam J. Burgasser, Michael C. Cushing, J. Davy Kirkpatrick, Christopher R. Gelino, Roger L. Griffith, Dagny L. Looper, Christopher Tinney, Robert A. Simcoe, John J. Bochanski, Michael F. Skrutskie, A. Mainzer, Maggie A. Thompson, Kenneth A. Marsh, James M. Bauer, Edward L. Wright. 2011-04-13. FIRE Spectroscopy of Five Late-type T Dwarfs Discovered with the Wide-field Infrared Survey Explorer. https://doi.org/10.1088/0004-637x/735/2/116

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