Protoplanetary disk fragmentation with varying radiative physics, initial conditions and numerical techniques

Understand

We review recent results of SPH simulations of gravitational instability in gaseous protoplanetary disks,emphasizing the role of thermodynamics in both isolated and binary systems.

• Contradictory results appeared in the literature regarding disk fragmentation at tens of AU from the central star are likely due to the different treatment of radiation physics as well as reflecting different initial conditions.
• Further progress on the subject requires extensive comparisons between different codes with the requirement that the same initial conditions are adopted.
• It is discussed how the local conditions of the disks undergoing fragmentation at $R < 25$ AU in recent SPH simulations are in rough agreement with the prediction of analytical models, with small differences being likely related to the inability of analytical models to account for the dynamics and thermodynamics of three-dimensional spiral shocks.