The young planet-mass object 2M1207b : a cool, cloudy, and methane-poor atmosphere

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DOIResolve DOI: http://doi.org/10.1088/2041-8205/735/2/L39
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TypeArticle
Journal titleThe Astrophysical Journal Letters
ISSN2041-8205
Volume735
Issue2
Article numberL39
PagesL39-1
Subjectbrown dwarfs; planetary systems; stars: atmospheres
AbstractThe properties of 2M1207b, a young (similar to 8 Myr) planet-mass companion, have lacked a satisfactory explanation for some time. The combination of low luminosity, red near-IR colors, and L-type near-IR spectrum (previously consistent with T(eff) similar to 1600 K) implies an abnormally small radius. Early explanations for the apparent underluminosity of 2M1207b invoked an edge-on disk or the remnant of a recent protoplanetary collision. The discovery of a second planet-mass object (HR8799b) with similar luminosity and colors as 2M1207b indicates that a third explanation, one of a purely atmospheric nature, is more likely. By including clouds, non-equilibrium chemistry, and low gravity, an atmosphere with effective temperature consistent with evolution cooling-track predictions is revealed. Consequently, 2M1207b, and others like it, requires no new physics to explain nor do they belong to a new class of objects. Instead they most likely represent the natural extension of cloudy substellar atmospheres down to low T(eff) and log(g). If this atmosphere only explanation for 2M1207b is correct, then very young planet-mass objects with near-IR spectra similar to field T dwarfs may be rare.
Publication date
LanguageEnglish
AffiliationNRC Herzberg Institute of Astrophysics; National Research Council Canada
Peer reviewedYes
NPARC number19734679
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Record identifier69f94ff2-e947-48b1-b2fa-5d97885e6d2f
Record created2012-03-28
Record modified2016-05-09
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