Volcanic exomoons and their potential observability

van der Wal, W. (Speaker), Steinke, T. (Speaker), Dirkx, D. (Speaker)

Activity: Talk or presentationTalk or presentation at a conference


Thousands of exoplanets have been discovered in the last decade, yet the detection of an exomoon remains elusive. Tidally heated exomoons are promising targets in the exomoon hunt. Vigorous tidal dissipation can result in widespread volcanism that can cause a signature in transits and, in extreme cases, rise the moon’s surface temperature hundreds of degrees making direct imaging possible. We consider tidal dissipation and heat transport in Io to Earth-sized rocky exomoons to obtain thermal equilibrium states for different orbital parameters. We show that surface heat fluxes 1 to 3 orders of magnitude higher than those of Io can be attained in the heat-pipe or magma ocean regime provided the moon orbits within few Roche radii of the planet and the eccentricity is high enough. To study the plausibility of these orbital configurations we consider a 2:1 resonance of a pair of exomoons around a gas giant. We investigate the thermal-orbital evolution of the system and find that it strongly depends on dissipation within the planet. For a Mars-sized exomoon we find that tidal dissipation can increase surface temperatures more than 400 K if the planet is highly dissipative but just for a few million years. Heat fluxes higher than those of Io can be maintained for several billion years providing ample opportunities for the outgassing of material and the formation of a plasma torus. The detection of a tidally-heated exomoon would not only give insight into the moon’s characteristics but also into the architecture of the satellite system and the interior structure of the planet.
Period9 Dec 2020
Event titleAGU Fall Meeting 2020
Event typeConference
Degree of RecognitionInternational