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Title: No Snowball on Habitable Tidally Locked Planets

Abstract

The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassingmore » fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.« less

Authors:
;  [1];  [2]
  1. Department of the Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)
  2. Centre for Planetary Sciences, Department of Physical and Environmental Sciences, University of Toronto at Scarborough, Toronto, ON M1C 1A4 (Canada)
Publication Date:
OSTI Identifier:
22663225
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 845; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; BIFURCATION; CARBON CYCLE; CARBON DIOXIDE; CONCENTRATION RATIO; ENERGY BALANCE; ORBITS; PLANETS; SATELLITE ATMOSPHERES; SATELLITES; STARS

Citation Formats

Checlair, Jade, Abbot, Dorian S., and Menou, Kristen, E-mail: jadecheclair@uchicago.edu. No Snowball on Habitable Tidally Locked Planets. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA80E1.
Checlair, Jade, Abbot, Dorian S., & Menou, Kristen, E-mail: jadecheclair@uchicago.edu. No Snowball on Habitable Tidally Locked Planets. United States. doi:10.3847/1538-4357/AA80E1.
Checlair, Jade, Abbot, Dorian S., and Menou, Kristen, E-mail: jadecheclair@uchicago.edu. Sun . "No Snowball on Habitable Tidally Locked Planets". United States. doi:10.3847/1538-4357/AA80E1.
@article{osti_22663225,
title = {No Snowball on Habitable Tidally Locked Planets},
author = {Checlair, Jade and Abbot, Dorian S. and Menou, Kristen, E-mail: jadecheclair@uchicago.edu},
abstractNote = {The TRAPPIST-1, Proxima Centauri, and LHS 1140 systems are the most exciting prospects for future follow-up observations of potentially inhabited planets. All of the planets orbit nearby M-stars and are likely tidally locked in 1:1 spin–orbit states, which motivates the consideration of the effects that tidal locking might have on planetary habitability. On Earth, periods of global glaciation (snowballs) may have been essential for habitability and remote signs of life (biosignatures) because they are correlated with increases in the complexity of life and in the atmospheric oxygen concentration. In this paper, we investigate the snowball bifurcation (sudden onset of global glaciation) on tidally locked planets using both an energy balance model and an intermediate-complexity global climate model. We show that tidally locked planets are unlikely to exhibit a snowball bifurcation as a direct result of the spatial pattern of insolation they receive. Instead, they will smoothly transition from partial to complete ice coverage and back. A major implication of this work is that tidally locked planets with an active carbon cycle should not be found in a snowball state. Moreover, this work implies that tidally locked planets near the outer edge of the habitable zone with low CO{sub 2} outgassing fluxes will equilibrate with a small unglaciated substellar region rather than cycling between warm and snowball states. More work is needed to determine how the lack of a snowball bifurcation might affect the development of life on a tidally locked planet.},
doi = {10.3847/1538-4357/AA80E1},
journal = {Astrophysical Journal},
number = 2,
volume = 845,
place = {United States},
year = {Sun Aug 20 00:00:00 EDT 2017},
month = {Sun Aug 20 00:00:00 EDT 2017}
}