Exoplanets & Exomoons

Extended Habitability Of Exoplanets Due To Subglacial Water

By Keith Cowing
Status Report
October 5, 2023
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Extended Habitability Of Exoplanets Due To Subglacial Water
Boundaries of the Habitable Zone under various climate and atmospheric models as a function of radiative flux received from the host star, relative to Earth. Dashed lines represent the extended boundaries due to subglacial liquid water suggested in this work: blue for the inner HZ boundary (night-side ice evaporates due to heat transport, the percentage marks the global transport parameter f) and violet for the outer one (Martian polar lakes). Solid green lines and green shading denote the conservative HZ boundaries: inner one (moist greenhouse) and outer one (maximum CO2 greenhouse), calculated using the 1-D climate model. Also marked is the Recent Venus boundary (dashed green line). The orange curve marks the tidal locking radius. Circles denote the terrestrial planets in the solarsystem and a few Earth-sized exoplanets orbiting M-dwarf stars. — astro-ph.EP

Considering subglacial liquid water, a significant extension of the classical Habitable Zone is obtained. Elaborating on the model of Wandel (2023) it is shown how an atmosphere and liquid water could survive on tidally locked planets closely orbiting an M-dwarf host, extending the Habitable Zone boundary inwards.

In addition, subglacial liquid water could extend the Habitable Zone beyond the outer boundary of the conservative Habitable Zone as well. These two results enhance the circumstellar region with a potential for liquid water well beyond the conservative boundaries of the classical Habitable Zone.

It is argued that the probable recent JWST detection of atmospheric water vapor on the rocky Earth-sized exoplanet GJ 486 b, along with earlier detections of water on other planets orbiting M-dwarf stars gives an empirical answer to the much-argued question, of whether such planets can support liquid water, organic chemistry and eventually life.

It is shown how water on terrestrial planets closely orbiting M-dwarf stars may sustain in a subglacial melting layer. Finally, the model is applied to a few exoplanets demonstrating how water detection may constrain their atmospheric properties.

Amri Wandel

Comments: 9 pages, 2 figures, accepted for publication in the Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2310.02452 [astro-ph.EP] (or arXiv:2310.02452v1 [astro-ph.EP] for this version)
Submission history
From: Amri Wandel
[v1] Tue, 3 Oct 2023 21:41:37 UTC (1,270 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻