2006/11/02 by D. Saumon, M. S. Marley, S. K. Leggett +8 · 6 citations
Physics and Astronomy · Social Sciences · #Astronomy and Astrophysical Research #Brown dwarf #Context (archaeology) #Educational Leadership and Practices #Infrared #Luminosity #Spectral line #Spectrograph #Stellar classification #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/510557
published as Astrophys.J.656:1136-1149,2007 · Accepted for publication in the Ap. J. 35 pages, including 12 figures (10 in color)
arxiv created 2006/11/02 · openalex publication_date 2007/02/14 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present new infrared spectra of the T8 brown dwarf 2MASS J04151954-0935066: 2.9-4.1 μm spectra obtained with the Infrared Camera and Spectrograph on the Subaru Telescope, and 5.2-14.5 μm spectra obtained with the Infrared Spectrograph on the Spitzer Space Telescope . We use these data and models to determine an accurate bolometric luminosity of log L bol / L ☉ = -5.67 and to constrain the effective temperature, gravity, mass, and age to 725-775 K, log g = 5.00-5.37, M = 33-58 M Jup , and age = 3-10 Gyr. We perform the same analysis using published 0.6-15 μm spectra for the T7.5 dwarf 2MASS J12171110-0311131, for which we find a metal-rich composition ([Fe/H] ~ 0.3), and log L bol / L ☉ = -5.31, T eff = 850-950 K, log g = 4.80-5.42, M = 25-66 M Jup , and age = 1-10 Gyr. These luminosities and effective temperatures straddle those determined with the same method and models for Gl 570D by Saumon et al. and make 2MASS J04151954-0935066 the coolest and least luminous T dwarf with well-determined properties. We find that synthetic spectra generated by the models reproduce the observed red through mid-infrared spectra of 2MASS J04151954-0935066 and 2MASS J12171110-0311131 very well, except for known discrepancies that are most likely due to the incomplete CH 4 opacities. Both objects show evidence of departures from strict chemical equilibrium, and we discuss this result in the context of other late T dwarfs in which disequilibrium phenomena have been observed.