Journal Article

Bayesian fitting of Taurus brown dwarf spectral energy distributions

N. J. Mayne, Tim J. Harries, John Rowe and David M. Acreman

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 423, issue 2, pages 1775-1804
Published in print June 2012 | ISSN: 0035-8711
Published online June 2012 | e-ISSN: 1365-2966 | DOI:
Bayesian fitting of Taurus brown dwarf spectral energy distributions

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We present derived stellar and disc parameters for a sample of Taurus brown dwarfs both with and without evidence of an associated disc. These parameters have been derived using an online fitting tool (, which includes a statistically robust derivation of uncertainties, an indication of parameter degeneracies and a complete treatment of the input photometric and spectroscopic observations.

The observations of the Taurus members with indications of disc presence have been fitted using a grid of theoretical models including detailed treatments of physical processes accepted for higher mass stars, such as dust sublimation, and a simple treatment of the accretion flux. This grid of models has been designed to test the validity of the adopted physical mechanisms, but we have also constructed models using parametrization, for example semi-empirical dust sublimation radii, for users solely interested in parameter derivation and the quality of the fit.

The parameters derived for the naked and disc brown dwarf systems are largely consistent with literature observations. However, our inner disc edge locations are consistently closer to the star than previous results and we also derive elevated accretion rates over non-spectral energy distribution based accretion rate derivations. For inner edge locations, we attribute these differences to the detailed modelling we have performed of the disc structure, particularly at the crucial inner edge where departures in geometry from the often adopted vertical wall due to dust sublimation (and therefore accretion flux) can compensate for temperature (and therefore distance) changes to the inner edge of the dust disc. In the case of the elevated derived accretion rates, in some cases, this may be caused by the intrinsic stellar luminosities of the targets exceeding that predicted by the isochrones we have adopted.

Keywords: techniques: photometric; catalogues; stars: evolution; stars: formation; Hertzsprung–Russell and colour–magnitude diagrams; stars: pre-main-sequence

Journal Article.  17262 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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