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Habitable Zones Around Main-Sequence Stars: Dependence on Planetary MassThe ongoing discoveries of extra-solar planets are unveiling a wide range of terrestrial mass (size) planets around their host stars. In this Letter, we present estimates of habitable zones (HZs) around stars with stellar effective temperatures in the range 2600 K-7200 K, for planetary masses between 0.1M and 5M. Assuming H2O-(inner HZ) and CO2-(outer HZ) dominated atmospheres, and scaling the background N2 atmospheric pressure with the radius of the planet, our results indicate that larger planets have wider HZs than do smaller ones. Specifically, with the assumption that smaller planets will have less dense atmospheres, the inner edge of the HZ (runaway greenhouse limit) moves outward (approx.10% lower than Earth flux) for low mass planets due to larger greenhouse effect arising from the increased H2O column depth. For larger planets, the H2O column depth is smaller, and higher temperatures are needed before water vapor completely dominates the outgoing long-wave radiation. Hence the inner edge moves inward (approx.7% higher than Earth's flux). The outer HZ changes little due to the competing effects of the greenhouse effect and an increase in albedo. New, three-dimensional climate model results from other groups are also summarized, and we argue that further, independent studies are needed to verify their predictions. Combined with our previous work, the results presented here provide refined estimates of HZs around main-sequence stars and provide a step toward a more comprehensive analysis of HZs.
Document ID
20160005749
Document Type
Reprint (Version printed in journal)
Authors
Kopparapu, Ravi Kumar (Pennsylvania State Univ. University Park, PA, United States)
Ramirez, Ramses M. (Pennsylvania State Univ. University Park, PA, United States)
Kotte, James Schottel (Pennsylvania State Univ. University Park, PA, United States)
Kasting, James F. (Pennsylvania State Univ. University Park, PA, United States)
Domagal-Goldman, Shawn (NASA Goddard Space Flight Center Greenbelt, MD United States)
Eymet, Vincent (Bordeaux Univ. France)
Date Acquired
May 3, 2016
Publication Date
May 15, 2014
Publication Information
Publication: The Astrophysical Journal Letters
Volume: 787
Issue: 2
Subject Category
Lunar and Planetary Science and Exploration
Report/Patent Number
GSFC-E-DAA-TN21697
Distribution Limits
Public
Copyright
Other
Keywords
main sequence starts
planetary mass
habitable zones