Numerical Studies of Star and Disk Formation

Abstract

Protoplanetary disks are ubiquitous and play a significant role in the early stages of star and planet formation; stars grow their mass from disks and conditions within the disk determine avail-able routes for planet formation. A testable theory of star and planet formation requires predictions of the range and relative distribution of disk properties. The goals of this thesis are to identify and understand the dominant physical processes that dictate star cluster and protostellar disk proper-ties and behavior using a series of numerical experiments. I motivated the rapid assembly of star-forming material by demonstrating the growth of the star cluster initial mass function through gravitational focusing (Chapter 2). Testing a sub-virial (cold) collapse model of star cluster formation,I showed that many large scale morphological and kinematic features of known nearby clusters can be reproduced (Chapter 3). Furthermore, I investigated the presence of kinematic substructure in clusters formed by cold collapse and found that stellar groups are likely to preserve evidence of early mass segregation through velocity coherent substructures seen in observed radial velocities(Chapter 4). Adding a sink-patch numerical construction to track the environs of star forming particles in the simulation, I modeled the formation of protostellar cores from the progenitor molecular cloud. In Chapter 5, I used the sink-patch construction to demonstrate the importance of the star formation environment when determining protostellar accretion rates and modeling the growth of the upper mass power law of the stellar initial mass function. In addition, I characterized how protostellar cores accrete angular momentum without (Chapter 6) and with (Chapter 7) the presence of magnetic fields. Together, this work has led to a statistical characterization of protostellar core properties and their accretion behaviors and set the stage for modeling disk formation with a set of physically motivated initial conditions that take into account the star forming environment.