The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present

By I. Ribas, É. Bolmont, F. Selsis, A. Reiners, J. Leconte, S. Raymond, S. Engle, E. Guinan, J. Morin, M. Turbet and 2 more. 2016

192 citations recorded by the source corpus.

Proxima b is a planet with a minimum mass of 1.3 MEarth orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass, active star and the Sun's closest neighbor. Here we investigate a number of factors related to the potential habitability of Proxima b and its ability to maintain liquid water on its surface. We set the stage by estimating the current high-energy irradiance of the planet and show that the planet currently receives 30 times more EUV radiation than Earth and 250 times more X-rays. We compute the time evolution of the star's spectrum, which is essential for modeling the flux received over Proxima b's lifetime. We also show that Proxima b's obliquity is likely null and its spin is either synchronous or in a 3:2 spin-orbit resonance, depending on the planet's eccentricity and level of triaxiality. Next we consider the evolution of Proxima b's water inventory. We use our spectral energy distribution to compute the hydrogen loss from the planet with an improved energy-limited escape formalism. Despite the high level of stellar activity we find that Proxima b is likely to have lost less than an Earth ocean's worth of hydrogen before it reached the HZ 100-200 Myr after its formation. The largest uncertainty in our work is the initial water budget, which is not constrained by planet formation models. We conclude that Proxima b is a viable candidate habitable planet.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/329163d72de3d25828673e25e469a6bd41c4ff73

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Citations in the corpus

Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life (2017, background): “…impacts of the ultraviolet (UV) and particle (flare) activity of these stars (Segura et al., 2003; Lammer et al., 2007; Davenport et al., 2016; Ribas et al., 2016; Airapetian et al., 2017), their premain sequence evolution (Ramirez and Kaltenegger, 2014; Luger and Barnes, 2015; Tian, 2015),…”
Is Proxima Centauri b Habitable? A Study of Atmospheric Loss (2017, methodology): “…from the stellar wind, the neutral hydrogen is neglected. bThe photoionization frequencies are rescaled to PCb values, using the EUV estimate from Ribas et al. (2016), the latter being around 33 times that received by the Earth. cRate coefficient from Fox & Sung (2001). atmosphere from Ma et al.…”
Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs (2017, background): “…in the HZ (Selsis et al. 2007; Wordsworth et al. 2010; Abe et al. 2011; Haqq-Misra & Kopparapu 2015; Barnes et al. 2016; Meadows et al. 2016; Ribas et al. 2016; Turbet et al. 2016; Bolmont et al. 2017), and studies such as these provide a valuable contribution in understanding, and…”
How to Characterize Habitable Worlds and Signs of Life (2017, background): “Without further observational constraints, a variety of atmospheres are possible for Proxima b (e.g., Meadows et al. 2016, Ribas et al. 2016, Turbet et al. 2016).”
The habitability of Proxima Centauri b II. Possible climates and Observability (2016, background): “Because Proxima b probably lost a massive amount of water during its early evolution around a pre-main sequence, active star (Ribas et al. 2016), we need to consider the possibility that the planet may now be rather dry.”
Atmospheric characterization of Proxima b by coupling the Sphere high-contrast imager to the Espresso spectrograph (2016, background): “The question of a habitable climate on Proxima b is a complex one that is being addressed by numerous studies (e.g. Ribas et al. 2016; Turbet et al. 2016; Meadows et al. 2016).”
Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System (2018, background): “…Schaefer et al. 2016; Wordsworth et al. 2018) or, depending on each planet’s magnetic field, lost to nonhydrodynamic, top-of-atmosphere processes over time (e.g., Khodachenko et al. 2007; Lammer et al. 2007, 2011; Ribas et al. 2016), such as the “electric wind” on Venus (Collinson et al. 2016).”
The Cosmic Shoreline: The Evidence that Escape Determines which Planets Have Atmospheres, and what this May Mean for Proxima Centauri B (2017, methodology): “Figure 1 shows insolation levels from Ribas et al. (2016) at 3 times: when Proxima was just 10 Myr old, when Proxima was 100 Myr old, and today.”
How Hospitable Are Space Weather Affected Habitable Zones? The Role of Ion Escape (2017, unknown): “The host star, Proxima Cen is characterized by an X-ray ﬂ ux comparable to the Sun at the maximum of solar activity and at the location of Proxima b , 0.05 au, the ﬂ ux should be enhanced by a factor of 60 F 0 ( Ribas et al. 2016 ) .”
Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets (2017, methodology): “We use the methods detailed in the section 4.6 of Ribas et al. (2016) to calculate the probability of spin-orbit resonance capture of the planets of TRAPPIST-1.”