“Formation and Evolution of Moons & Exomoons”

Hagai Perets (Technion)
Wednesday, 1440, Lecture Room 106

Moons orbiting gas and ice giants are likely formed through collisional growth of planetesimals in circumplanetary disks. Previous studies have shown that the observed (regular) co-planar satellite systems orbiting the Solar system gas and ice giants can be formed in circumplanetary disks, where both accretion and collisions as well as gas drag/migration play important role in the evolution. These studies did not produce irregular, eccentric and/or highly inclined moons. Our studies show that similar in-situ formation of moons can produce both the regular satellites as well as retrograde and high eccentricity satellites such as Triton, when allowing for satellites growth in the external regions of the circumplanetary disks (neglected before) in some cases. Using the same models, we also explore what are the largest moons that can be formed around gas giants, when allowing for more massive circumplanetary disks and/or more massive planets than the Solar system planets; which could be relevant for exomoon formation conditions. We find that relatively large moons can be formed, up to Mars size moons. To date none of our simulations produce Earth-size or larger moons, but further studies of the phase space involved are yet to be done.