Yoram Lithwick, Yanqin Wu
Planetary systems discovered by the Kepler space telescope exhibit an intriguing feature. While the period ratios of adjacent low-mass planets appear largely random, there is a significant excess of pairs that lie just wide of resonances and a deficit on the near side. We demonstrate that this feature naturally arises when two near-resonant planets interact in the presence of weak dissipation that damps eccentricities. The two planets repel each other as orbital energy is lost to heat. This moves near-resonant pairs just beyond resonance, by a distance that reflects the integrated dissipation they experienced over their lifetimes. We find that the observed distances may be explained by tidal dissipation if tides are efficient (tidal quality factor ~10). Once the effect of resonant repulsion is accounted for, the initial orbits of these low mass planets show little preference for resonances. This is a strong constraint on their origin.
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http://arxiv.org/abs/1204.2555
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