Dissertations, Theses, and Capstone Projects

Date of Degree

6-2025

Document Type

Master's Thesis

Degree Name

Master of Science

Program

Astrophysics

Advisor

Mordecai-Mark Mac Low

Advisor

Ugo Lebreuilly

Committee Members

Ally Sheffield

Subject Categories

Other Astrophysics and Astronomy | Physical Processes | The Sun and the Solar System

Keywords

planet formation, streaming instability, Class 0/I, MHD

Abstract

While it is clear that planets form in protoplanetary disks, fragmentation and the radial drift of pebbles inhibit the growth of grains to planetesimals. To overcome these barriers, effective localized dust clumping on a short enough time scale is required. One promising solution to this problem is the streaming instability. Streaming instability is only triggered with a large enough dust-to-gas ratio and grain size. Though it is unknown when and where those conditions are met in protoplanetary disks, recent studies have indicated that planetary cores likely require early formation to match detected exoplanet system masses, so that we need to shift our focus to young Class 0/I disks to study the initial conditions for planet formation. To investigate this, we use global models of disk formation and evolution run with the non-ideal magnetohydrodynamic version of RAMSES, an adaptive mesh refinement code, with a dust dynamics solver and a treatment of dust growth similar to a monodisperse model. In the simulations, we see disks form early within 10 kyr, and we investigate their physical attributes such as mass and radius fluctuation. We find that the criteria required by streaming instability are met in wide regions within our simulated models, within the first 20 kyr of the simulation time. Regions susceptible to streaming instabilities that enclose the star show larger grain sizes, while outer disk regions susceptible to streaming instabilities have a higher dust-to-gas ratio.

In Chapter 1, I will elaborate on the greater context the work is placed in, explaining the observational and theoretical ideas that planet formation are based in. I will detail the importance of using simulations to investigate planet formation. In Chapter 2, I will describe the methods used by me and my advisors to investigate the question of whether we can see criteria necessary for the streaming instability to be triggered within protoplanetary disks. In Chapter 3, I will present my results of different models from the thesis work, including the evolution of the disks and whether the streaming instability criteria are met in these disks. In Chapter 4, I will discuss the results of the work and briefly outline some caveats.

Download

Share

COinS