Revised Fluxes for Gliese 229B

Leggett, S. K.; Toomey, Douglas W.; Geballe, T. R.; Brown, R. H.

doi:10.1086/312049

Cited by 70 publications

(94 citation statements)

References 12 publications

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“…Extending from the red branch of the dwarf track, comprised of late M dwarfs (Leggett, Allard, & Hauschildt 1998), are L dwarfs (triangles) identiÐed in 2MASS data . At the opposite end of the main sequence track lie Gliese 229B (Leggett et al 1999 ; square) and the majority of T dwarfs (circles) identiÐed by 2MASS and SDSS. These objects lie just below the densest region of near-infrared color space, occupied by early-type (OÈG) stars. ""…”

Section: The 2mass T Dwarf Searchmentioning

confidence: 99%

“…L dwarf (triangles) and T dwarf (circles) colors are shown with error bars, based on 2MASS photometry. Colors for Gliese 229B (square) are taken from Leggett et al (1999). The locations of S-, C-, and M-type asteroids are indicated by hash-marked regions (Sykes et al 2000).…”

Section: The 2mass T Dwarf Searchmentioning

confidence: 99%

“…This is nearly one-third the original estimate from Burgasser et al (1999), and implies only 35 T dwarfs with detectable by 2MASS over the J [ K s [ 0.6 whole sky. If we adopt a distance limit based on the absolute brightness of Gliese 229B (Leggett et al 1999 ; M J \ and our J-band magnitude limit, we derive a 15.51^0.09) space density of 4.2 ] 10~3 pc~3.…”

Section: New T Dwarfsmentioning

confidence: 99%

See 2 more Smart Citations

The Spectra of T Dwarfs. I. Near‐Infrared Data and Spectral Classification

Burgasser

Kirkpatrick

Brown

et al. 2002

ApJ

415

513

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We present near-infrared spectra for a sample of T dwarfs, including 11 new discoveries made using the 2 Micron All Sky Survey. These objects are distinguished from warmer (L-type) brown dwarfs by the presence of methane absorption bands in the 1È2.5 km spectral region. A Ðrst attempt at a near-infrared classiÐcation scheme for T dwarfs is made, based on the strengths of and bands and the CH 4 H 2 O shapes of the 1.25, 1.6, and 2.1 km Ñux peaks. Subtypes T1 VÈT8 V are deÐned, and spectral indices useful for classiÐcation are presented. The subclasses appear to follow a decreasing scale, based on T eff the evolution of and bands and the properties of L and T dwarfs with known distances. CH 4 H 2 O However, we speculate that this scale is not linear with spectral type for cool dwarfs, due to the settling of dust layers below the photosphere and subsequent rapid evolution of spectral morphology around K. Similarities in near-infrared colors and continuity of spectral features suggest that T eff D 1300È1500 the gap between the latest L dwarfs and earliest T dwarfs has been nearly bridged. This argument is strengthened by the possible role of as a minor absorber, shaping the K-band spectra of the latest CH 4 L dwarfs. Finally, we discuss one peculiar T dwarf, 2MASS 0937]2931, which has very blue nearinfrared colors due to suppression of the 2.1 km peak. The feature is likely (J [ K s \ [0.89^0.24) caused by enhanced collision-induced absorption in a high-pressure or low-metallicity photosphere. H 2

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Section: The 2mass T Dwarf Searchmentioning

confidence: 99%

Section: The 2mass T Dwarf Searchmentioning

confidence: 99%

Section: New T Dwarfsmentioning

confidence: 99%

See 1 more Smart Citation

The Spectra of T Dwarfs. I. Near‐Infrared Data and Spectral Classification

Burgasser

Kirkpatrick

Brown

et al. 2002

ApJ

415

513

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“…Carbon monoxide in GI 229B. The spectrum of GI 229B is shown as a thick solid line (Oppenheimer et al 1998;Leggett et al 1999). The 4.5 -5/-Lm spectrum is flux-calibrated using the M' photometry of Golimowski et al (2002).…”

Section: Non-equilibrium Chemistry In Brown Dwarf Atmospheresmentioning

confidence: 99%

Non-equilibrium Chemistry in the Atmospheres of Brown Dwarfs

Saumon

Marley

Lodders

et al. 2003

Symp. - Int. Astron. Union

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Abstract. Carbon monoxide and ammonia have been detected in the spectrum of GI 229B at abundances that differ substantially from those obtained from chemical equilibrium. Vertical mixing in the atmosphere is a mechanism that can drive slowly reacting species out of chemical equilibrium. We explore the effects of vertical mixing as a function of mixing efficiency and effective temperature on the chemical abundances in the atmospheres of brown dwarfs and on their spectra. The models compare favorably with the observational evidence and indicate that vertical mixing plays an important role in brown dwarf atmospheres.

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“…Spectral Ðtting and models (e.g., Leggett, Allard, & Hauschildt 1998 ;Chabrier et al 2000 ;Marley 2000) demonstrate that this is because of the progressive appearance of more silicate dust in the cooling brown dwarf atmospheres. Yet the cooler T-type brown dwarfs, such as Gl 229B, have blue colors in J[K (e.g., Leggett et al 1999 ;Tsvetanov et al 2000). The spectra and colors of these cool brown dwarfs can only be Ðt by atmosphere models that assume the silicate dust has settled below the visible atmosphere (e.g., Allard et al 1996 ;Marley et al 1996 ;Tsuji et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Precipitating Condensation Clouds in Substellar Atmospheres

Ackerman

Marley

2001

ApJ

777

1,283

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We present a method to calculate vertical proÐles of particle size distributions in condensation clouds of giant planets and brown dwarfs. The method assumes a balance between turbulent di †usion and sedimentation in horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are compared with results from previous methods. An adjustable parameter describing the efficiency of sedimentation allows the new model to span the range of predictions made by previous models. Calculations for the Jovian ammonia cloud are consistent with observations. Example calculations are provided for water, silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant planet. We Ðnd that precipitating cloud decks naturally account for the characteristic trends seen in the spectra of Land T-type ultracool dwarfs.

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Revised Fluxes for Gliese 229B

Cited by 70 publications

References 12 publications

The Spectra of T Dwarfs. I. Near‐Infrared Data and Spectral Classification

The Spectra of T Dwarfs. I. Near‐Infrared Data and Spectral Classification

Non-equilibrium Chemistry in the Atmospheres of Brown Dwarfs

Precipitating Condensation Clouds in Substellar Atmospheres

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