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Photospheric Properties of L and T Dwarfs

Published online by Cambridge University Press:  26 May 2016

S. K. Leggett
Affiliation:
Joint Astronomy Centre, 660 N. A 'ohoku Place, Hilo Hawaii 96720
X. Fan
Affiliation:
Institute for Advanced Study, Olden Lane, Princeton NJ 08540
T. R. Geballe
Affiliation:
Gemini Observatory, 670 N. A 'ohoku Place, Hilo Hawaii 96720
D. A. Golimowski
Affiliation:
Johns Hopkins University, 3701 San Martin Drive, Baltimore MD 21218
G. R. Knapp
Affiliation:
Princeton University Observatory, Princeton NJ 08544

Abstract

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The photospheric spectra of all L and T dwarfs contain strong molecular bands and alkali absorption features, and those of L and early T dwarfs are also affected by dust. Although work on atmospheric models is addressing the treatment of dust, and is increasing the completeness of molecular opacity linelists, the effective temperatures of L and T dwarfs cannot be derived confidently from the modelled spectral energy distributions. However, because the radii of brown dwarfs older than 0.1 Gyr vary little with mass, measurements of intrinsic luminosity (i.e. total integrated flux and parallax) accurately determine effective temperature. Using this method we find a well constrained relationship between the effective temperatures of L and T dwarfs and spectral type, but with temperature nearly constant from L7 to T4. More work is required to determine the uniqueness of this relationship and to constrain the masses and ages of brown dwarfs.

Type
Part 7. Atmospheres and Internal Structure
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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