Near-infrared photometry and spectroscopy of L and T dwarfs: The effects of clouds, gravity, and effective temperature

D. A. Golimowski, S. K. Leggett, M. S. Marley, X. Fan, T. R. Geballe, G. R. Knapp

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

We 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 JH K-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.

Original languageEnglish (US)
Pages (from-to)575-578
Number of pages4
JournalEuropean Space Agency, (Special Publication) ESA SP
Issue number560 I
StatePublished - Aug 29 2005
Event13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun - Hamburg, Germany
Duration: Jul 5 2004Jul 9 2004

Keywords

  • Infrared: stars
  • Stars: fundamental parameters
  • Stars: late-type
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Aerospace Engineering
  • Space and Planetary Science

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