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Mantle Convection in Tidally-Locked Planets

8 Oct 2013, 10:00 UTC
Mantle Convection in Tidally-Locked Planets NASA/Ames/JPL-Caltech
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Observations over the years have shown that short-period terrestrial planets appear to be rather common around stars. Most of these planets are expected to be tidally-locked and are likely to undergo processes in planetary evolution that do not occur for the terrestrial planets in our solar system. For a tidally-locked planet, one day is equal to one year. As a result, one hemisphere will always be facing its host star while the other hemisphere will never be. This creates a fixed hot substellar region and a fixed cold antistellar region.Figure 1: Kepler-20e and Kepler-20f compared to Venus and Earth. Both Kepler-20e and Kepler-20f orbit a Sun-like star, Kepler-20, closer than Mercury orbits the Sun. The two planets are likely to be tidally-locked with scorching dayside temperatures. Credit: NASA/Ames/JPL-Caltech.A study done by S. E. Gelman et al. (2011) identifies two main stages of mantle convection evolution for tidally-locked terrestrial planets. The first stage is a transient stage which involves a lithospheric temperature and thickness dichotomy emerging between the planet’s substellar and antistellar hemispheres. Basically, the substellar lithosphere warms and becomes thinner, while the antistellar lithosphere cools and thickens. During this stage, mantle upwellings and downwellings are pervasive throughout the planet’s interior. ...

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