Thursday 22 Jun 2017The role of disc self-gravity in the formation of planets and planetary systems

Prof. Ken Rice - University of Edinburgh

Physics, 4th Floor 14:00-15:00

It's now clear that planets form in discs around young stars. Given recent high-resolution observations of these systems, there are indications that the planet formation process actually starts when the system is still very young. At these early times it is quite likely that the disc mass will be a reasonable fraction of the mass of the central protostar. As such, the disc's own self-gravity will play a role in its evolution; it will likely be susceptible to the growth of the gravitational instability. This instability will manifest itself through the growth of spiral density waves and, potentially, the direct formation of gravitationally bound clumps that could contract to form protoplanets. However, the latter process probably only operates in the outer parts of protostellar discs where the disc properties satisfy the conditions for fragmentation. On the other hand, the presence of spiral density waves may play a role in the growth of planet building material, even if this instability does not form planets directly. In this talk I will discuss the role that disc self-gravity may play in the formation of planets, both direct and indirect, and will discuss if disc fragmentation could have formed some of the known exoplanets, in particular those on wide orbits, typically found by direct imaging.

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