Dissertation/Thesis Abstract

The Destructive Birth of Massive Stars & Massive Star Clusters
by Rosen, Anna L., Ph.D., University of California, Santa Cruz, 2017, 289; 10274404
Abstract (Summary)

The injection of energy and momentum into the interstellar medium by young massive stars’ intense radiation fields and their fast, radiatively driven winds can have a profound influence on their formation and environment. Massive star forming regions are rare and highly obscured, making the early moments of their formation difficult to observe. Instead, we must turn to theory to elucidate the physics involved in the formation of massive stars and massive star clusters (MSCs), which can host thousands of massive stars. In my thesis, I developed analytical and numerical techniques to study the formation of massive stars and how stellar wind feedback affects the dynamics of gas that surrounds MSCs. To estimate the initial rotation rates of massive stars at birth, I developed a protostellar angular momentum evolution model for accreting protostars to determine if magnetic torques can spin down massive stars during their formation. I found that magnetic torques are insufficient to spin down massive stars due to their short formation times and high accretion rates. Radiation pressure is likely the dominate feedback mechanism regulating massive star formation. Therefore detailed simulation of the formation of massive stars requires an accurate treatment of radiation. For this purpose, I developed a new, highly accurate radiation algorithm that properly treats the absorption of the direct radiation field from stars and the re-emission and processing by interstellar dust. With this new tool, I performed a suite of three-dimensional adaptive mesh refinement radiation-hydrodynamic simulations of the formation of massive stars from collapsing massive pre-stellar cores. I found that mass is channeled to the massive star via dense infalling filaments that are uninhibited by radiation pressure and gravitational and Rayleigh-Taylor instabilities. To determine the importance of stellar wind feedback in young MSCs, I used observations to constrain a range of kinetic energy loss channels for the hot gas produced by the shock-heating of stellar winds to explain the low X-ray luminosities observed in Hii regions. I demonstrated that the energy injected by stellar winds is not a significant contributor to stellar feedback in young MSCs.

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Indexing (document details)
Advisor: Krumholz, Mark R.
Commitee: Foley, Ryan, Ramirez-Ruiz, Enrico
School: University of California, Santa Cruz
Department: Astronomy & Astrophysics
School Location: United States -- California
Source: DAI-B 79/01(E), Dissertation Abstracts International
Subjects: Astrophysics, Astronomy
Keywords: Computational astrophysics, Massive stars, Star formation, Stellar feedback, Theory
Publication Number: 10274404
ISBN: 9780355129847