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Title: THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE

Abstract

The properties of 2M1207b, a young ({approx}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{sub eff} {approx} 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{sub 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.

Authors:
 [1]; ;  [2];  [3]
  1. Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001 (United States)
  2. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)
  3. National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)
Publication Date:
OSTI Identifier:
21562543
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 735; Journal Issue: 2; Other Information: DOI: 10.1088/2041-8205/735/2/L39; Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; INFRARED SPECTRA; LUMINOSITY; PLANETS; STELLAR ATMOSPHERES; ATMOSPHERES; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; SPECTRA

Citation Formats

Barman, Travis S., Macintosh, Bruce, Konopacky, Quinn M., and Marois, Christian, E-mail: barman@lowell.edu. THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE. United States: N. p., 2011. Web. doi:10.1088/2041-8205/735/2/L39.
Barman, Travis S., Macintosh, Bruce, Konopacky, Quinn M., & Marois, Christian, E-mail: barman@lowell.edu. THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE. United States. doi:10.1088/2041-8205/735/2/L39.
Barman, Travis S., Macintosh, Bruce, Konopacky, Quinn M., and Marois, Christian, E-mail: barman@lowell.edu. Sun . "THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE". United States. doi:10.1088/2041-8205/735/2/L39.
@article{osti_21562543,
title = {THE YOUNG PLANET-MASS OBJECT 2M1207b: A COOL, CLOUDY, AND METHANE-POOR ATMOSPHERE},
author = {Barman, Travis S. and Macintosh, Bruce and Konopacky, Quinn M. and Marois, Christian, E-mail: barman@lowell.edu},
abstractNote = {The properties of 2M1207b, a young ({approx}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{sub eff} {approx} 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{sub 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.},
doi = {10.1088/2041-8205/735/2/L39},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 735,
place = {United States},
year = {2011},
month = {7}
}