We have completed a study (Rosotti et al 2017) involving the longest term integration of a planet + protoplanetary disc system that has ever been conducted (totaling 3 x 105 planetary orbits) with a view to understanding whether discs can drive significant planetary eccentricity. This is a fundamental issue for interpreting data on exoplanetary eccentricity. We have shown that there is a complicated exchange of eccentricity between the disc and the planet on these timescales which can be understood in terms of two secular modes that are subject to long term damping and pumping. While there is still much to be understood about the processes responsible for mode damping and pumping, our study has shown that eccentricity growth cannot be determined via the sort of short timescale (< 1000 orbit) simulations that have been conducted previously. These GPU accelerated calculations pave the way for a more comprehensive exploration of long term eccentricity driving of planets in discs.
In Haworth et al 2017 we have presented the first calculations that demonstrate that discs may lose significant mass from their outer regions as a result of photoevaporation by ambient far ultraviolet radiation, even in regions where the ambient radiation levels are very low. This study involved a novel code, TORUS-3DPDR which solves for radiative transfer in dust, hydrodynamics and photochemistry within the outflowing wind and which demonstrates that the extended CO emission observed over many 100s of AU from the disc IM Lupi is well explained by a photoevaporative wind.
