GLIESE 581D IS THE FIRST DISCOVERED TERRESTRIAL-MASS EXOPLANET IN THE HABITABLE ZONE

By R. Wordsworth, Francois Forget, F. Selsis, Ehouarn Millour, B. Charnay, Jean-Baptiste Madeleine. 2011

204 citations recorded by the source corpus.

It has been suggested that the recently discovered exoplanet GJ581d might be able to support liquid water due to its relatively low mass and orbital distance. However, GJ581d receives 35% less stellar energy than Mars and is probably locked in tidal resonance, with extremely low insolation at the poles and possibly a permanent night side. Under such conditions, it is unknown whether any habitable climate on the planet would be able to withstand global glaciation and/or atmospheric collapse. Here we present three-dimensional climate simulations which demonstrate that GJ581d will have a stable atmosphere and surface liquid water for a wide range of plausible cases, making it the first confirmed super-Earth (exoplanet of 2–10 Earth masses) in the habitable zone. We find that atmospheres with over 10 bar CO2 and varying amounts of background gas (e.g., N2) yield global mean temperatures above 0°C for both land and ocean-covered surfaces. Based on the emitted IR radiation calculated by the model, we propose observational tests that will allow these cases to be distinguished from other possible scenarios in the future.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets (2017, background): “The GCM includes an up-to-date generalized radiative transfer that takes into account the absorption and scattering by the atmosphere, the clouds and the surface from visible to far-infrared wavelengths, as described in Wordsworth et al. (2011).”
Global modelling of the early Martian climate under a denser CO2 atmosphere: Water cycle and ice evolution (2012, methodology): “Our radiative transfer scheme was similar to that used in previous studies [e.g., Wordsworth et al., 2011].”
THE ULTRAVIOLET RADIATION ENVIRONMENT AROUND M DWARF EXOPLANET HOST STARS (2012, background): “GJ 581d is a super-Earth (MP ≈ 6 M⊕) that resides on the outer edge of the habitable zone (HZ; aP = 0.22 AU; Wordsworth et al. 2011; von Braun et al. 2011).”
HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: NEW ESTIMATES (2013, background): “…emission spectra of Earth-like planets in a 1D model (Kitzmann et al. 2011a,b), while others studied the habitability of specific systems, particularly Gl 581, in 1D (Wordsworth et al. 2010; Von Paris et al. 2011a; Kaltenegger et al. 2011a) and 3D (Wordsworth et al. 2011; Pierrehumbert 2011).”
3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability and habitability (2013, methodology): “The method used to produce our radiative transfer model is similar to Wordsworth et al. (2011).”
WATER LOSS FROM TERRESTRIAL PLANETS WITH CO2-RICH ATMOSPHERES (2013, unknown): “ tested the eects of clouds in their model and came to similar conclusions about their eect on climate. Some improvement in cloud modeling can be provided by 3D planetary climate simulations (e.g., Wordsworth et al. 2011), which allows the eects of the large-scale dynamics to be taken into account. ”
THE MUSCLES TREASURY SURVEY. I. MOTIVATION AND OVERVIEW (2016, background): “GJ 581d is a super-Earth (Mplan ≈ 6 M⊕) that resides on the outer edge of the habitable zone (HZ; aplan = 0.22 AU; Wordsworth et al. 2011; von Braun et al. 2011).”
The habitability of Proxima Centauri b II. Possible climates and Observability (2016, background): “The shorter stellar day in 2:1 (11.2 Earth days compared to 22.4) which weakens day/night contrasts is compensated by the higher rotation rate, which weakens equator-to-pole heat redistribution (Wordsworth et al. 2011; Kaspi & Showman 2015).”
Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3‐D GCM (2013, unknown): “This model has been used to study early climates in the solar system [ Forget et al. , 2012; Wordsworth et al. , 2012] as well as climates on extrasolar planets [ Wordsworth et al. , 2011; Leconte et al. , 2013].”
STABILIZING CLOUD FEEDBACK DRAMATICALLY EXPANDS THE HABITABLE ZONE OF TIDALLY LOCKED PLANETS (2013, background): “Near the cold outer edge of the HZ (Kasting et al. 1993), CO2 ice clouds can scatter outgoing thermal radiation back to the surface, also causing warming (Forget & Pierrehumbert 1997; Wordsworth et al. 2011).”
A dynamically-packed planetary system around GJ 667C with three super-Earths in its habitable zone (2013, background): “Considerable work has shown that thicker atmospheres are able to redistribute dayside heat to produce clement conditi s (Joshi et al. 1997; Joshi 2003; Edson et al. 2011; Pierrehumbert 2011; Wordsworth et al. 2011).”
Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST (2017, background): “…to be illustrative of a broad range of atmospheres, not definitive estimates of liquid-water habitable zones, which have previously been published in many other relevant works (see, e.g., Kasting et al. 1993; Selsis et al. 2007; Wordsworth et al. 2011; Kopparapu et al. 2013; Shields et al. 2016).”
The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “…atmospheric absorption of near-IR radiation will increase surface temperatures, which could increase the habitable surface area of a planet (e.g., Wordsworth et al., 2010, 2011), though CO2 condensation will become more likely and collisional line broadening more critical above 1-2 bar of CO2…”