The Stability of Exomoons in the Habitable Zone

Sammanfattning: This is an analysis of all the planets at exoplanets.org, with the goal of finding out how many of these that could possibly have moons supporting life. I have first calculated the ranges of the habitable zones (HZ:s) for the stars in the archive, using the Runaway Greenhouse model for the inner limit, and the Maximum Greenhouse model for the outer limit, as presented by Kopparapu et al. (2013A). Then I investigate the stability of moons in systems with multiple planets, by inspecting the separation between the planets in terms of their the mutual Hill radii. I calculate how many habitable moons (of 0.3M Earth-masses) individual planets can have, by first placing one at the edge of the planet's Roche lobe, and then another a variable number of mutual Hill radii further in, and then repeating until I reach the point where the moon or the planet fills its own Roche lobe. Finally, I attempt to fit hypothetical planets in the systems with 'gaps' in the habitable zone between discovered planets. A total of 19 confirmed planets were found in habitable zones, out of which 8 are in multiplanetary systems. Out of all 19, all except one were seemingly able to have at least one habitable moon, and a majority even able to have more than 10. Out of all confirmed planets, over 90% seemed to be able to have moons of habitable size, with almost 40% being able to have 10 or more. These numbers can be considered as upper limits, but even as such are quite optimistic as they rely on perfectly circular orbits, and are arrived at while ignoring destabilising phenomena such as mean-motion resonances.