STABILIZING CLOUD FEEDBACK DRAMATICALLY EXPANDS THE HABITABLE ZONE OF TIDALLY LOCKED PLANETS

By Jun Yang, N. Cowan, Dorian S. Abbot. 2013

272 citations recorded by the source corpus.

The habitable zone (HZ) is the circumstellar region where a planet can sustain surface liquid water. Searching for terrestrial planets in the HZ of nearby stars is the stated goal of ongoing and planned extrasolar planet surveys. Previous estimates of the inner edge of the HZ were based on one-dimensional radiative-convective models. The most serious limitation of these models is the inability to predict cloud behavior. Here we use global climate models with sophisticated cloud schemes to show that due to a stabilizing cloud feedback, tidally locked planets can be habitable at twice the stellar flux found by previous studies. This dramatically expands the HZ and roughly doubles the frequency of habitable planets orbiting red dwarf stars. At high stellar flux, strong convection produces thick water clouds near the substellar location that greatly increase the planetary albedo and reduce surface temperatures. Higher insolation produces stronger substellar convection and therefore higher albedo, making this phenomenon a stabilizing climate feedback. Substellar clouds also effectively block outgoing radiation from the surface, reducing or even completely reversing the thermal emission contrast between dayside and nightside. The presence of substellar water clouds and the resulting clement surface conditions will therefore be detectable with the James Webb Space Telescope.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/d26c86450773181cbad4c26692f8e6cc7fd22e74

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In Astronomy and Astrophysics

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).”
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…”
Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs (2017, methodology): “The climates of these slowrotating worlds are strongly influenced by the circulation regime, as convection, clouds, and horizontal transport are fundamentally altered (Yang et al. 2013; Kopparapu et al. 2016).”
The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “…planets, increased cloud cover is formed at the substellar point (providing it is located over an ocean), reflecting incident stellar flux, and buffering these planets against runaway greenhouse states compared to planets whose substellar point varies greatly with time (Yang et al., 2013).”
HABITABLE ZONES AROUND MAIN-SEQUENCE STARS: DEPENDENCE ON PLANETARY MASS (2014, background): “Specifically, a recent study by Yang et al. (2013) proposed that stabilizing cloud feedback can expand the inner HZ (IHZ) to roughly twice the stellar flux found from 1D climate calculations for tidally locked planets or planets that are in synchronous rotation around low mass stars.”
THE INNER EDGE OF THE HABITABLE ZONE FOR SYNCHRONOUSLY ROTATING PLANETS AROUND LOW-MASS STARS USING GENERAL CIRCULATION MODELS (2016, methodology): “Recently, Yang et al. (2013, 2014a) used the Community Atmosphere Model (CAM) from the National Center of Atmospheric Research, Boulder CO, to simulate an Earth-size water-rich planet in various spin-orbit configurations.”
Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets (2017, background): “The two inner planets of the system (TRAPPIST-1b and c) are likely too hot to sustain global oceans of liquid water (Kopparapu et al. 2013; Yang et al. 2013; Kopparapu et al. 2016).”
The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present (2016, background): “For a synchronized planet, we locate the inner edge at S p = 1.5 S ⊕ (the protection of the substellar point by clouds allows the planet to be much closer, e.g., Yang et al. 2013; Kopparapu 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, background): “GCM-based estimates of the onset of the runaway range between 1.1 to 1.7 solar constants, with details of cloud structure and cloud physics and planetary rotation responsible for much of the variance (Abe et al. 2011; Yang et al. 2013; Leconte et al. 2013a,b; Wolf and Toon 2015; Way 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): “Yang et al. (2013) demonstrated that a tidally-locked M dwarf planet might develop a persistent cloud patch above the sub-stellar point.”
The habitability of Proxima Centauri b II. Possible climates and Observability (2016, background): “= 0.123 M ), defined as the range of orbital distances within which a planet can possibly maintain liquid water on its surface (Kasting et al. 1993; Kopparapu et al. 2013; Leconte et al. 2013a; Yang et al. 2013; Kopparapu et al. 2014, 2016).”