Presentation #101.02 in the session “Evolution and Migration in Exoplanet Systems: Sub-Neptunes and Super-Earths”.
Early discoveries of giant exoplanets orbiting near their host stars and exoplanets in or near mean motion resonances were interpreted as evidence for migration and its crucial role in the beginnings of planetary systems. In addition, long-scale migration has been invoked to explain systems of planets in mean motion resonant chains consisting of three or more planets linked by integer period ratios. However, recent studies have questioned the prevalence of planet migration since one major hallmark of migration has been orbital resonances, but most systems are not truly in resonance. We re-characterize the six-planet system Kepler-80 by directly forward modeling and fitting the lightcurve of the system. We find that previous studies over-estimated the two outer planet masses due to the unknown signal of the sixth planet. We also find that the four-planet resonant chain initially confirmed by MacDonald et. al 2016 does indeed exist, but we cannot confirm a five-planet chain with new planet g. We also model six additional systems with three or more planets near a chain of period commensurabilities in search of resonances. We are able to confirm the five-planet resonant chain of K2-138 and characterize the system and its planets. We are also able to identify numerous pairs of planets that are likely in a two-body resonance. These six systems would greatly benefit from additional data to more readily constrain their properties and dynamics.