The early evolution of protostellar disks: fragmentation, episodic accretion, planet formation and other unexpected effects

Eduard Vorobyev

Gravitational instability and fragmentation in the early evolution of embedded protostellar disks is a common occurrence. Nevertheless, the importance of disk fragmentation has not been fully appreciated until recently. It has long been known that disk fragmentation may lead to the formation of gas giants and brown dwarfs on wide orbits. However, there is a lot more than the planet/BD formation that is directly caused by disk fragmentation. I will demonstrate how disk fragmentation can trigger episodic accretion onto the star, an effect that can explain both the spread and magnitude of luminosities in young star-forming regions. Ejection of very-low-mass stars, brown dwarfs and even giant planets into the intracluster medium can also be triggered by disk fragmentation. Another unexpected consequence of disk fragmentation is the flattening of the mass accretion -- stellar mass relation for the T Tauri stars. Finally, I will show how disk fragmentation can account for the presence of crystalline silicates in the Solar System comets.