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تسجيل مستخدم جديدThe potential for tidally heated icy and temperate moons around exoplanets
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Caleb A. Scharf
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Moons of giant planets may represent an alternative to the classical picture of habitable worlds. They may exist within the circumstellar habitable zone of a parent star, and through tidal energy dissipation they may also offer alternative habitable zones, where stellar insolation plays a secondary, or complementary, role. We investigate the potential extent of stable satellite orbits around a set of 74 known extrasolar giant planets located beyond 0.6 AU from their parent stars - where moons should be long-lived with respect to removal by stellar tides. Approximately 60% of these giant planets can sustain satellites or moons in bands up to $sim 0.04$ AU in width. For comparison, the Galiean satellites extend to $sim 0.013$ AU. We investigate the stellar insolation that moons would experience for these exoplanet systems, and the implications for sublimation loss of volatiles. We find that between 15 and 27% of {em all} known exoplanets may be capable of harboring small, icy, moons. In addition, some 22-28% of all known exoplanets could harbor moons within a ``sublimation zone, with insolation temperatures between 273 K and 170 K. A simplified energy balance model is applied to the situation of temperate moons, maintained by a combination of stellar insolation and tidal heat flow. We demonstrate that large moons ($>0.1 $M$_{oplus}$), at orbital radii commensurate with those of the Galilean satellites, could maintain temperate, or habitable, surface conditions during episodes of tidal heat dissipation of the order 1-100 times that currently seen on Io. (Abridged).
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