Time: 　　
　  2:00pm, May 28th (Friday)

Location: 　　
　  3rd floor, middle conference room

Abstract:

Planetesimals are kilometer-sized bodies that are the buiding blocks for terrestrial planets and giant planet cores, yet their formation remains a mystery. The main difficulty comes from the meter-size barrier: meter-sized bodies suffer from rapid radial drift towards the star on time scale of about 100 years. Recently, it was found that the including the back-reaction from solids to gas leads to a powerful drag instability: the streaming instability (SI). SI efficiently concentrate decimeter to meter sized solids into dense clumps, triggering gravitational collapse to form planetesimals directly, bypassing the meter barrier. I will describe my recent work on hybrid simulations of the SI, in which we have systematically explored the parameter space of solid-gas dynamics in the dead zone of protoplanetary disks where magnetorotational instability is quenched due to the low ionization level. These results suggest that planetesimal formation may be less difficult than previously thought.