Constraining the Evolution of Protoplanetary Disks in Clustered Star-formation Environments
Publisher
The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
Protoplanetary disks are the birthplaces of planetary systems, and obtaining a complete picture of how planets form hinges on an understanding of how disks evolve throughout the Galaxy. State-of-the-art radio interferometers now provide the sensitivity and angular resolution needed to detect large samples of protoplanetary disks in rich clusters, the most common sites of star formation in our Galaxy. While recent radio-interferometric surveys have begun mapping disk properties in nearby clusters, the majority of previous investigations have focused on measuring the dust content of protoplanetary disks rather than the molecular gas, which dominates the disk mass budget and kinematics. In this dissertation, I have used the Atacama Large Millimeter/submillimeter Array (ALMA) and Karl G. Jansky Very Large Array (VLA) to determine the molecular gas masses, sizes, kinematics, compositions, and mass-loss rates of protoplanetary disks in the nearby clusters of Orion. I first present deep, high resolution ALMA CO $J = 3 - 2$ and HCO$^+$ $J=4 - 3$ observations that have mapped a large portion of the Orion Nebula Cluster (ONC), and show that the gas disks that are detected with these observations are smaller than the disks typically found in lower-mass star-forming regions. I then outline a novel procedure that utilizes thermochemical and line radiative transfer modeling to constrain the total disk masses, gas-to-dust ratios, and central stellar masses of the ALMA-detected ONC gas disks. I explain how the derived gas masses and gas-to-dust ratios differ from the values derived for disks in lower-mass star-forming regions, and describe what these results imply for planet formation in the ONC. Finally, I introduce my work with the VLA to constrain the photoevaporative mass-loss rates of disks in the NGC 1977 cluster. I compare the derived mass-loss rates with the values measured in other star-forming regions, and discuss their implications for Galactic star and planet formation.Type
Electronic Dissertationtext
Degree Name
Ph.D.Degree Level
doctoralDegree Program
Graduate CollegeAstronomy