Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects of Clouds, Gravity, and Effective Temperature

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dc.creatorGolimowski, D. A.
dc.creatorLeggett, S. K.
dc.creatorMarley, M. S.
dc.creatorGeballe, X. Fan. T. R.
dc.creatorKnapp, G. R.
dc.date2004-09-17
dc.date.accessioned2026-07-07T02:14:39Z
dc.date.available2026-07-07T02:14:39Z
dc.descriptionWe present new JHKL'M' photometry on the MKO system for a large sample of L and T dwarfs identified from SDSS and 2MASS and classified according to the scheme of Geballe et al. (2002). We have compiled a sample of 105 L and T dwarfs that are uniformly classified and measured on a single photometric system. The scattered JHK spectral indices and colors of L dwarfs are likely caused by variations in the altitudes, distributions, and thicknesses of condensate clouds. Scatter in the H-K colors of late T dwarfs probably reflects the sensitivity of the K-band flux to pressure induced H_2 opacity, which itself is sensitive to surface gravity. The M' luminosities of late-T dwarfs are 1.5-2.5 times fainter than predicted under conditions of chemical equilibrium. We have computed L_bol and T_eff for 42 L and T dwarfs whose trigonometric parallaxes have been measured. We find that T_eff ~ 1450 K for types L7-T4, which supports recent models that attribute the changing JHK-band luminosities and spectral features across the L-T transition to rapid changes in the condensate clouds over a narrow range of T_eff. We compute T_eff = 600-750 K for 2MASS 0415-0935 (T9), which supplants Gl 570D as the coolest known brown dwarf.
dc.description4 pages, 8 figures, to appear in the Proceedings of the 13th Cool Stars Workshop, ESA Special Publications Series, 2005
dc.identifierhttps://arxiv.org/abs/astro-ph/0409429
dc.identifierhttp://arxiv.org/abs/astro-ph/0409429
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/8199
dc.subjectAstrophysics
dc.titleNear-Infrared Photometry and Spectroscopy of L and T Dwarfs: the Effects of Clouds, Gravity, and Effective Temperature
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