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Physics & Astronomy Colloquium – Spring 2022 – Chao-Chin Yang
March 9 @ 3:30 pm - 5:00 pm
Speaker: Chao-Chin Yang (UNLV)
Title: From Pebbles to Planets: A Tale of Protoplanetary Disks and Planetsimal Formation
Abstract: Even though thousands of extrasolar planetary systems have been detected, a comprehensive picture of how planets are formed from their natal protoplanetary disks remains to be drawn. One of the most challenging stages is the formation of kilometer-scale planetesimals from centi-/milli-meter-sized pebbles in the disk. These pebbles suffer from problematically rapid inward drifts and poor sticking efficiencies due to fragmentation and bouncing at collisions. On the other hand, modern facilities such as ALMA just begun to be able to resolve nearby protoplanetary disks, giving us clues of how pebbles are distributed in these disks, offering unprecedented opportunities of advancing our knowledge of protoplanetay disks and planetesimal formation.
I will review our current understanding of the particle-gas dyanmics in protoplanetary disks and its consequences on planetesimal formation. Specifically, I will examine how and under what conditions pebbles can actively concentrate themselves to high density for planetesimals to form, the initial mass function of planetesimals, and the effects of MHD turbulence. I will also elaborate on how we are in a position to connect theories of planetesimal formation to observations of protoplanetary disks and the properties of the minor bodies in the Solar System.