The Best Planets to Harbor Detectable Exomoons

Abstract

Abstract Albeit the discovery of thousands of extrasolar planets, so far no exomoon has been found. This may be due to a lack of dynamical investigation of the best regions around the planets for a satellite to exist. We provide a list of the best candidates of exomoon hosting planets using the Kepler database. The inner and outer stability boundaries of an exomoon orbital semimajor axis were calculated for all planets. The first limit is the minimum distance to the planet such that the object will not disintegrate due to tidal forces, the Roche limit, that depends on the moon density. The outer boundary is the region where an exomoon may exist for a long period of time. Both limits are a function of the planet mass, calculated from its radius inferred from the observed transit depth. Each planet has been tested with the exomoon mass estimated for three values of moon–planet distance, and the moon radius for five different densities (ice, ice–rock, rock, rock–iron, and iron), totalling 15 different combinations. For the planet to be considered a suitable exomoon host, the system has to pass three criteria: (i) the planet–moon distance should be greater than the Roche limit; (ii) the system center-of-mass is within the planet; and (iii) the moon transit depth is greater than twice the light-curve noise (Combined Differential Photometric Precision). After processing all the data, 54 planets were left from the Kepler list with putative “visible” satellites, thus providing the best candidates for an exomoon search.