Moon formation in the circumplanetary habitable zone
Zoltán Dencs
ELTE Gothard Astrophysical Observatory, Szombathely, Hungary


Among the few thousand discovered exoplanets, a significant number of planets are orbiting in the habitable zone of the host star. Most of these planets are gaseous giants, which do not have a rocky surface and a water reservoir, essential for life as we know it. The search for a habitable environment can be extended to the moons of the giant planets. There is no confirmed discovery of exomoons yet, only a few promising candidates are known. However, theories suggest that moon formation is a natural process in planetary systems. To answer where and how the moons can be formed, the 3DNAL research group set up models, in which Earth-like exomoons can be formed around giant planets. We also study the habitability of the newly formed moons.
We investigate the efficiency of moon formation with numerical N-body simulations. Moons are formed in a circumplanetary belt, which consists of protomoons and satellitesimals. Giant planets are orbiting at different distances from the host star in our models.
Our results show that the time-scale for moon formation is shorter around close-in planets than at larger distances from the star, however, a significant number of protomoons and satellitesimals escape from the planet, decreasing moon formation efficiency. We find that more moons can form around planets on wide orbits than around planets close to the star, however, they are less massive. I will show the details of our main findings in my presentation.
To determine the habitability of the synthetic moons, we calculate the incident stellar radiation and the tidal heating flux that can arise in moons depending on their orbital and physical parameters. Based on our calculations, half a hundred confirmed giant planets can harbor habitable moons beyond the outer edge of the circumstellar habitable zone.

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