Habitable Moist Atmospheres on Terrestrial Planets near the Inner Edge of the Habitable Zone around M Dwarfs
By R. Kopparapu, E. Wolf, Giada N. Arney, N. Batalha, J. Haqq‐Misra, S. Grimm, K. Heng. 2017
176 citations recorded by the source corpus.
Terrestrial planets in the habitable zones (HZs) of low-mass stars and cool dwarfs have received significant scrutiny recently. Transit spectroscopy of such planets with the James Webb Space Telescope (JWST) represents our best shot at obtaining the spectrum of a habitable planet within the next decade. As these planets are likely tidally locked, improved 3D numerical simulations of such planetary atmospheres are needed to guide target selection. Here we use a 3D climate system model, updated with new water-vapor absorption coefficients derived from the HITRAN 2012 database, to study ocean-covered planets at the inner edge of the HZ around late M to mid-K stars ( ). Our results indicate that these updated water-vapor coefficients result in significant warming compared to previous studies, so the inner HZ around M dwarfs is not as close as suggested by earlier work. Assuming synchronously rotating Earth-sized and Earth-mass planets with background 1 bar atmospheres, we find that planets at the inner HZ of stars with undergo the classical “moist greenhouse” ( mixing ratio in the stratosphere) at significantly lower surface temperature (∼280 K) in our 3D model compared with 1D climate models (∼340 K). This implies that some planets around low-mass stars can simultaneously undergo water loss and remain habitable. However, for stars with , planets at the inner HZ may directly transition to a runaway state, while bypassing the moist greenhouse water loss entirely. We analyze transmission spectra of planets in a moist greenhouse regime and find that there are several prominent features, including a broad feature between 5 and 8 μm, within JWST MIRI instrument range. Thus, relying only on standard Earth-analog spectra with 24 hr rotation period around M dwarfs for habitability studies will miss the strong features that one would expect to see on synchronously rotating planets around M dwarf stars, with JWST.
Subfields: Astronomy and Astrophysics, Atmospheric Science
View Paper: https://www.semanticscholar.org/paper/c0f2291f95ce7542e32ac253989c803541c645de
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Citations in the corpus
- Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, background): “A detailed review of the various factors affecting habitability of terrestrial exoplanets can be found in various recent works (97, 228, 130, 95, 119, 235, 99).”