Habitability of planets on eccentric orbits: the limits of the mean flux approximation
International audience Contrary to Earth, which has a small orbital eccentricity, some exoplanets discovered in the insolation habitable zone (HZ) have high orbital eccentricities (e.g., up to an eccentricity of $\sim0.97$ for HD~20782~b). This raises the question of the capacity of these planets to...
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Online Access: | https://hal.science/hal-01306074 https://doi.org/10.1051/0004-6361/201628073 |
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ftinsu:oai:HAL:hal-01306074v1 2023-11-12T04:18:33+01:00 Habitability of planets on eccentric orbits: the limits of the mean flux approximation Libert, Anne-Sophie, Leconte, J. Selsis, Franck Bolmont, Emeline Namur Center for Complex Systems Namur (NaXys) Université de Namur Namur (UNamur) ECLIPSE 2016 Laboratoire d'Astrophysique de Bordeaux Pessac (LAB) Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) 2016 https://hal.science/hal-01306074 https://doi.org/10.1051/0004-6361/201628073 en eng HAL CCSD EDP Sciences info:eu-repo/semantics/altIdentifier/arxiv/1604.06091 info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201628073 hal-01306074 https://hal.science/hal-01306074 ARXIV: 1604.06091 BIBCODE: 2016A&A.591A.106B doi:10.1051/0004-6361/201628073 ISSN: 0004-6361 EISSN: 1432-0756 Astronomy and Astrophysics - A&A https://hal.science/hal-01306074 Astronomy and Astrophysics - A&A, 2016, 591, pp.id.A106. ⟨10.1051/0004-6361/201628073⟩ [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] info:eu-repo/semantics/article Journal articles 2016 ftinsu https://doi.org/10.1051/0004-6361/201628073 2023-10-18T16:29:07Z International audience Contrary to Earth, which has a small orbital eccentricity, some exoplanets discovered in the insolation habitable zone (HZ) have high orbital eccentricities (e.g., up to an eccentricity of $\sim0.97$ for HD~20782~b). This raises the question of the capacity of these planets to host surface liquid water. In order to assess the habitability of an eccentric planet, the mean flux approximation is often used. It states that a planet on an eccentric orbit is called habitable if it receives on average a flux compatible with the presence of surface liquid water. However, as the planets do experience important insolation variations over one orbit and even spend some time outside the HZ for high eccentricities, the question of their habitability might not be as straightforward. We performed a set of simulations using the Global Climate Model LMDz, exploring the limits of the mean flux approximation when varying the luminosity of the host star and the eccentricity of the planet. We computed the climate of tidally locked ocean covered planets with orbital eccentricity from 0 to 0.9 receiving a mean flux equal to Earth's, around stars of luminosity ranging from $L_\odot$ to $10^{-4}~L_\odot$. Using here a definition of habitability based on the presence of surface liquid water, we find that most of the planets considered can sustain surface liquid water on the dayside with an ice cap on the nightside. However, for high eccentricity and high luminosity, planets cannot sustain surface liquid water during the whole orbital period. They completely freeze at apoastron and when approaching periastron an ocean appears around the substellar point. We conclude that the higher the eccentricity and the higher the luminosity of the star, the less reliable the mean flux approximation. Article in Journal/Newspaper Ice cap Institut national des sciences de l'Univers: HAL-INSU Astronomy & Astrophysics 591 A106 |
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Institut national des sciences de l'Univers: HAL-INSU |
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ftinsu |
language |
English |
topic |
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] |
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[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] Libert, Anne-Sophie, Leconte, J. Selsis, Franck Bolmont, Emeline Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
topic_facet |
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] |
description |
International audience Contrary to Earth, which has a small orbital eccentricity, some exoplanets discovered in the insolation habitable zone (HZ) have high orbital eccentricities (e.g., up to an eccentricity of $\sim0.97$ for HD~20782~b). This raises the question of the capacity of these planets to host surface liquid water. In order to assess the habitability of an eccentric planet, the mean flux approximation is often used. It states that a planet on an eccentric orbit is called habitable if it receives on average a flux compatible with the presence of surface liquid water. However, as the planets do experience important insolation variations over one orbit and even spend some time outside the HZ for high eccentricities, the question of their habitability might not be as straightforward. We performed a set of simulations using the Global Climate Model LMDz, exploring the limits of the mean flux approximation when varying the luminosity of the host star and the eccentricity of the planet. We computed the climate of tidally locked ocean covered planets with orbital eccentricity from 0 to 0.9 receiving a mean flux equal to Earth's, around stars of luminosity ranging from $L_\odot$ to $10^{-4}~L_\odot$. Using here a definition of habitability based on the presence of surface liquid water, we find that most of the planets considered can sustain surface liquid water on the dayside with an ice cap on the nightside. However, for high eccentricity and high luminosity, planets cannot sustain surface liquid water during the whole orbital period. They completely freeze at apoastron and when approaching periastron an ocean appears around the substellar point. We conclude that the higher the eccentricity and the higher the luminosity of the star, the less reliable the mean flux approximation. |
author2 |
Namur Center for Complex Systems Namur (NaXys) Université de Namur Namur (UNamur) ECLIPSE 2016 Laboratoire d'Astrophysique de Bordeaux Pessac (LAB) Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Libert, Anne-Sophie, Leconte, J. Selsis, Franck Bolmont, Emeline |
author_facet |
Libert, Anne-Sophie, Leconte, J. Selsis, Franck Bolmont, Emeline |
author_sort |
Libert, Anne-Sophie, |
title |
Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
title_short |
Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
title_full |
Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
title_fullStr |
Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
title_full_unstemmed |
Habitability of planets on eccentric orbits: the limits of the mean flux approximation |
title_sort |
habitability of planets on eccentric orbits: the limits of the mean flux approximation |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://hal.science/hal-01306074 https://doi.org/10.1051/0004-6361/201628073 |
genre |
Ice cap |
genre_facet |
Ice cap |
op_source |
ISSN: 0004-6361 EISSN: 1432-0756 Astronomy and Astrophysics - A&A https://hal.science/hal-01306074 Astronomy and Astrophysics - A&A, 2016, 591, pp.id.A106. ⟨10.1051/0004-6361/201628073⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/arxiv/1604.06091 info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201628073 hal-01306074 https://hal.science/hal-01306074 ARXIV: 1604.06091 BIBCODE: 2016A&A.591A.106B doi:10.1051/0004-6361/201628073 |
op_doi |
https://doi.org/10.1051/0004-6361/201628073 |
container_title |
Astronomy & Astrophysics |
container_volume |
591 |
container_start_page |
A106 |
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1782335145764716544 |