Discovery of Four Field Methane (T-type) Dwarfs with 2MASS

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dc.creatorBurgasser, A. J.
dc.creatorKirkpatrick, J. D.
dc.creatorBrown, M. E.
dc.creatorReid, I. N.
dc.creatorGizis, J. E.
dc.creatorDahn, C. C.
dc.creatorMonet, D. G.
dc.creatorBeichman, C. A.
dc.creatorLiebert, J.
dc.creatorCutri, R. M.
dc.creatorSkrutskie, M. F.
dc.date1999-07-01
dc.date1999-08-03
dc.date.accessioned2026-07-07T02:32:15Z
dc.date.available2026-07-07T02:32:15Z
dc.descriptionWe report the discovery of four field methane (T-type) brown dwarfs using 2MASS survey data. One additional methane dwarf, previously discovered by SDSS, was also identified. Near-infrared spectra clearly show the 1.6 and 2.2 um CH4 absorption bands characteristic of objects with T_eff < 1300 K, as well as broadened H2O bands at 1.4 and 1.9 um. Comparing the spectra of these objects with Gl 229B, we propose that all new 2MASS T dwarfs are warmer than 950 K, in order from warmest to coolest: 2MASS J1217-03, J1225-27, J1047+21 and J1237+65. Based on this preliminary sample, we find a warm T dwarf surface density of 0.0022 T dwarfs/sq. deg., 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 L dwarf sample from Kirkpatrick et al. (1999).
dc.description12 pages, 2 figures, 2 tables, to appear in ApJ Letters v. 520
dc.identifierhttps://arxiv.org/abs/astro-ph/9907019
dc.identifierhttp://arxiv.org/abs/astro-ph/9907019
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/14444
dc.subjectAstrophysics
dc.titleDiscovery of Four Field Methane (T-type) Dwarfs with 2MASS
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