Suppression of the Water Ice and Snow Albedo Feedback on Planets Orbiting Red Dwarf Stars and the Subsequent Widening of the Habitable Zone

Joshi, MM and Haberle, RM (2012) Suppression of the Water Ice and Snow Albedo Feedback on Planets Orbiting Red Dwarf Stars and the Subsequent Widening of the Habitable Zone. Astrobiology, 12 (1). pp. 3-8. ISSN 1531-1074

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Abstract

M stars comprise 80% of main sequence stars, so their planetary systems provide the best chance for finding habitable planets, that is, those with surface liquid water. We have modeled the broadband albedo or reflectivity of water ice and snow for simulated planetary surfaces orbiting two observed red dwarf stars (or M stars), using spectrally resolved data of Earth's cryosphere. The gradual reduction of the albedos of snow and ice at wavelengths greater than 1 µm, combined with M stars emitting a significant fraction of their radiation at these same longer wavelengths, means that the albedos of ice and snow on planets orbiting M stars are much lower than their values on Earth. Our results imply that the ice/snow albedo climate feedback is significantly weaker for planets orbiting M stars than for planets orbiting G-type stars such as the Sun. In addition, planets with significant ice and snow cover will have significantly higher surface temperatures for a given stellar flux if the spectral variation of cryospheric albedo is considered, which in turn implies that the outer edge of the habitable zone around M stars may be 10–30% farther away from the parent star than previously thought

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia > Faculty of Science > Research Centres > Tyndall Centre for Climate Change Research
University of East Anglia > Faculty of Science > Research Groups > Climatic Research Unit
University of East Anglia > Faculty of Science > Research Groups > Volcanoes@UEA
University of East Anglia > Faculty of Science > Research Groups > Marine and Atmospheric Sciences
University of East Anglia > Faculty of Science > Research Groups > Meteorology, Oceanography and Climate Dynamics
University of East Anglia > Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences
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Depositing User: Rhiannon Harvey
Date Deposited: 01 Feb 2012 10:44
Last Modified: 12 Sep 2018 12:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/36695
DOI: 10.1089/ast.2011.0668

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