STRONG DEPENDENCE OF THE INNER EDGE OF THE HABITABLE ZONE ON PLANETARY ROTATION RATE

By Jun Yang, Gwenaël Boué, D. Fabrycky, Dorian S. Abbot. 2014

184 citations recorded by the source corpus.

Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for determining the mean planetary climate. Here we investigate this idea using a three-dimensional general circulation model with a sophisticated cloud scheme. We find that slowly rotating planets (like Venus) can maintain an Earth-like climate at nearly twice the stellar flux as rapidly rotating planets (like Earth). This suggests that many exoplanets previously believed to be too hot may actually be habitable, depending on their rotation rate. The explanation for this behavior is that slowly rotating planets have a weak Coriolis force and long daytime illumination, which promotes strong convergence and convection in the substellar region. This produces a large area of optically thick clouds, which greatly increases the planetary albedo. In contrast, on rapidly rotating planets a much narrower belt of clouds form in the deep tropics, leading to a relatively low albedo. A particularly striking example of the importance of rotation rate suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e0f05e4124808eeaac599a13ce6a14649ed23665

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In Astronomy and Astrophysics

1. D. Charbonneau
2. C. Dressing
3. R. Kopparapu
4. E. Wolf
5. J. Johnson
6. S. Ballard
7. V. Meadows
8. Aomawa L. Shields

Citations in the corpus

• Assessing the Habitability of the TRAPPIST-1 System Using a 3D Climate Model (2017, background): “…model version previously for studying a variety of Earth-like atmospheres (Wolf & Toon 2013, 2014a, 2014b, 2015; Wolf et al. 2017), and CAM4 has been frequently used elsewhere for studying slow rotating planets around M-dwarf stars (Yang et al. 2013, 2014; Kopparapu et al. 2016; Wang et al. 2016).”
• THE OCCURRENCE OF POTENTIALLY HABITABLE PLANETS ORBITING M DWARFS ESTIMATED FROM THE FULL KEPLER DATASET AND AN EMPIRICAL MEASUREMENT OF THE DETECTION SENSITIVITY (2015, background): “Even more optimistically, Table 6 includes HZ occurrence rates using the cloudy inner HZ from Yang et al. (2014), two choices of desert world albedos from Zsom et al. (2013), and the convenient limits of 0.25 − 4 F⊕ used by Petigura et al. (2013a).”
• Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs (2017, methodology): “This means that the inner edges of the habitable zone defined by Yang et al. (2014) and Kopparapu et al. (2016) are both placed too close to the host star.”
• THE INNER EDGE OF THE HABITABLE ZONE FOR SYNCHRONOUSLY ROTATING PLANETS AROUND LOW-MASS STARS USING GENERAL CIRCULATION MODELS (2016, methodology): “Following a methodology similar to that of Yang et al. (2014), we moved planets closer to the star (by increasing the stellar flux) until the the model becomes unstable.”
• The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “Studies have shown that cloud cover fraction is a function of planetary rotation rate, with larger cloud cover created on planets (with oceans) rotating at slower periods (Yang et al., 2014), as shown in Figure 8 for tidally vs. non-tidally locked planets.”
• Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System (2018, methodology): “We assume the modeled atmospheres are stable against collapse on the night side, due to sufficiently high atmospheric mass (10–100 bar) to reduce day–night temperature contrasts (Turbet et al. 2018) or ocean circulation for the 1bar aqua planets (Hu & Yang 2014).”
• Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life (2017, methodology): “…using more advanced three-dimensional (3D) general circulation models (GCMs), however, suggests more optimistic limits at the inner edge of the HZ (Yang et al., 2013, 2014; Leconte et al., 2013a, 2013b; Kopparapu et al., 2016; Shields et al., 2016b) while also showing perhaps more pessimistic…”