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, Xiaohui Fan, T. R. Geballe, G. R. Knapp

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

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)
Title of host publicationEuropean Space Agency, (Special Publication) ESA SP
EditorsF. Favata, G.A.J. Hussain, B. Battrick
Pages575-578
Number of pages4
Edition560 I
StatePublished - 2005
Event13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun - Hamburg, Germany
Duration: Jul 5 2004Jul 9 2004

Other

Other13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun
CountryGermany
CityHamburg
Period7/5/047/9/04

Fingerprint

Photometry
Luminance
Gravitation
Spectroscopy
Color
Infrared radiation
Opacity
Fluxes
Temperature

Keywords

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

ASJC Scopus subject areas

  • Aerospace Engineering

Cite this

Golimowski, D. A., Leggett, S. K., Marley, M. S., Fan, X., Geballe, T. R., & Knapp, G. R. (2005). Near-infrared photometry and spectroscopy of L and T dwarfs: The effects of clouds, gravity, and effective temperature. In F. Favata, G. A. J. Hussain, & B. Battrick (Eds.), European Space Agency, (Special Publication) ESA SP (560 I ed., pp. 575-578)

Near-infrared photometry and spectroscopy of L and T dwarfs : The effects of clouds, gravity, and effective temperature. / Golimowski, D. A.; Leggett, S. K.; Marley, M. S.; Fan, Xiaohui; Geballe, T. R.; Knapp, G. R.

European Space Agency, (Special Publication) ESA SP. ed. / F. Favata; G.A.J. Hussain; B. Battrick. 560 I. ed. 2005. p. 575-578.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Golimowski, DA, Leggett, SK, Marley, MS, Fan, X, Geballe, TR & Knapp, GR 2005, Near-infrared photometry and spectroscopy of L and T dwarfs: The effects of clouds, gravity, and effective temperature. in F Favata, GAJ Hussain & B Battrick (eds), European Space Agency, (Special Publication) ESA SP. 560 I edn, pp. 575-578, 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, Hamburg, Germany, 7/5/04.
Golimowski DA, Leggett SK, Marley MS, Fan X, Geballe TR, Knapp GR. Near-infrared photometry and spectroscopy of L and T dwarfs: The effects of clouds, gravity, and effective temperature. In Favata F, Hussain GAJ, Battrick B, editors, European Space Agency, (Special Publication) ESA SP. 560 I ed. 2005. p. 575-578
Golimowski, D. A. ; Leggett, S. K. ; Marley, M. S. ; Fan, Xiaohui ; Geballe, T. R. ; Knapp, G. R. / Near-infrared photometry and spectroscopy of L and T dwarfs : The effects of clouds, gravity, and effective temperature. European Space Agency, (Special Publication) ESA SP. editor / F. Favata ; G.A.J. Hussain ; B. Battrick. 560 I. ed. 2005. pp. 575-578
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AU - Fan, Xiaohui

AU - Geballe, T. R.

AU - Knapp, G. R.

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N2 - 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.

AB - 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.

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