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The habitability of Proxima Centauri b II. Possible climates and Observability

dc.contributor.authorTURBET, Martin,
hal.structure.identifierECLIPSE 2016
dc.contributor.authorLECONTE, J.
hal.structure.identifierECLIPSE 2016
dc.contributor.authorSELSIS, Franck
hal.structure.identifierNamur Center for Complex Systems [Namur] [NaXys]
dc.contributor.authorBOLMONT, Emeline,
hal.structure.identifierLaboratoire de Météorologie Dynamique (UMR 8539) [LMD]
dc.contributor.authorFORGET, Francois,
hal.structure.identifierDpto. de Organización de Empresas, Escuela Técnica Superior de Ingeniería Industrial de Barcelona
dc.contributor.authorRIBAS, Ignasi,
hal.structure.identifierECLIPSE 2016
dc.contributor.authorRAYMOND, Sean N.
dc.contributor.authorANGLADA-ESCUDÉ, Guillem,
dc.date.issued2016-08
dc.identifier.issn0004-6361
dc.description.abstractEnRadial velocity monitoring has found the signature of a $M \sin i = 1.3$~M$_\oplus$ planet located within the Habitable Zone of Proxima Centauri, (Anglada-Escud\'e et al. 2016). Despite a hotter past and an active host star the planet Proxima~b could have retained enough volatiles to sustain surface habitability (Ribas et al. 2016). Here we use a 3D Global Climate Model to simulate Proxima b's atmosphere and water cycle for its two likely rotation modes (1:1 and 3:2 resonances) while varying the unconstrained surface water inventory and atmospheric greenhouse effect. We find that a broad range of atmospheric compositions can allow surface liquid water. On a tidally-locked planet with a surface water inventory larger than 0.6 Earth ocean, liquid water is always present, at least in the substellar region. Liquid water covers the whole planet for CO$_2$ partial pressures $\gtrsim 1$~bar. For smaller water inventories, water can be trapped on the night side, forming either glaciers or lakes, depending on the amount of greenhouse gases. With a non-synchronous rotation, a minimum CO$_2$ pressure is required to avoid falling into a completely frozen snowball state if water is abundant. If the planet is dryer, $\sim$0.5~bar of CO$_2$ would suffice to prevent the trapping of any arbitrary small water inventory into polar ice caps. More generally, any low-obliquity planet within the classical habitable zone of its star should be in one of the climate regimes discussed here. We use our GCM to produce reflection/emission spectra and phase curves. We find that atmospheric characterization will be possible by direct imaging with forthcoming large telescopes thanks to an angular separation of $7 \lambda/D$ at 1~$\mu$m (with the E-ELT) and a contrast of $\sim 10^{-7}$. The magnitude of the planet will allow for high-resolution spectroscopy and the search for molecular signatures.
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enAstrophysics - Earth and Planetary Astrophysics
dc.title.enThe habitability of Proxima Centauri b II. Possible climates and Observability
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361/201629577
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Planétologie et astrophysique de la terre [astro-ph.EP]
dc.identifier.arxiv1608.06827
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.pageid.A112
bordeaux.volume596
bordeaux.peerReviewedoui
hal.identifierhal-01359518
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-01359518v1
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