ASIAA Summer Students Program
ASIAA Summer Student Program 2022
July 1 - August 31

2022 Project Description

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Dust dynamics in magnetized protoplanetary disks
This project can be carried out remotely.

Astrophysical Fluid Dynamics
Dust Dynamics
Planet Formation
Planetesimal Formation
Protoplanetary Disks
Theoretical Astrophysics


Min-Kai Lin, Chun-Yen Hsu
Find out more about supervisors on ASIAA website

Task Description and Goals

Planets are formed from dust grains in gaseous protoplanetary disks around young stars. A key step in this process is the formation of planetesimals — km-sized or larger bodies capable of accreting smaller pebbles or attracting other planetesimals through gravity. A popular mechanism invoked for planetesimal formation is the streaming instability (Youdin & Goodman, 2005). However, the theory of the streaming instability usually assumes an unmagnetized gas for simplicity, whereas real protoplanetary disks are expected to be magnetized, albeit subject to non-ideal magneto-hydrodynamical (MHD) effects. An open question is then how do planetesimals form under such conditions?

Recently, Lin & Hsu (2022) generalized the theory of the streaming instability to magnetized disks with Ohmic resistivity and found that magnetic fields have potentially important effects on the instability. In this project, the student will further extend this theory to account for two additional non-ideal MHD effects, namely the Hall effect and ambipolar diffusion, which play key roles in the gas dynamics of protoplanetary disks. The student will investigate how the streaming instability is affected by these non-ideal MHD effects and explore if they lead to new instabilities. The student will then apply the new theory to assess the efficiency of planetesimal formation in physical disk models.

The student will perform mathematical analyses, write a simple program to solve the relevant equations, carry out numerical calculations, and analyze results. Successful completion of this project is expected to lead to publication. See Chen & Lin (2020) for a similar study that also began as a summer student project and was published in The Astrophysical Journal.

Required Background

Physical and/or mathematical sciences, linear algebra, basic scientific programming and plotting, English communication skills

Advantageous: fluid dynamics, applied mathematics, scientific writing

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