This movie below is of one of the simulations presented in Dunhill & Stamatellos (MNRAS, submitted). Using 3D SPH simulations we studied the interaction between young giant planets and gravitationally unstable discs using the β-cooling prescription. We find that the planet is quickly driven eccentric as it interacts with turbulent structures in the disc. This provides an effective method for seeding an initial non-zero eccentricity. Goldreich & Sari (2003) and Duffell & Chiang (2015) both independently found that further eccentricity growth by disc torques is made possible if the planet is initially eccentric. These results combined suggest that there may be a difference in the final eccentricity distribution for planets formed by gravitational fragmentation from those formed by core accretion.
The movie below shows a comparison between the β = 10 (left) and β = 25 (right) run, demonstrating that faster cooling (lower β) discs with more pronounced GI structures are more efficient at growing the eccentricity. In each case we start at t = β orbits as the planet is kept on a fixed circular orbit until this time. The movie was rendered using SPLASH.