Dissertations, Theses, and Capstone Projects

Date of Degree

9-2025

Document Type

Master's Thesis

Degree Name

Master of Science

Program

Astrophysics

Advisor

Thavisha Dharmawardena

Advisor

Jared Goldberg

Committee Members

Allyson Sheffield

Subject Categories

Astrophysics and Astronomy | Computer Sciences | Data Science | Stars, Interstellar Medium and the Galaxy

Keywords

red supergiants, circumstellar material, massive stars, Betelgeuse, ALMA, data analysis

Abstract

Betelgeuse is a red supergiant star visible in the constellation Orion. Its windy and highly convective surface results in a complicated mass loss pattern difficult to understand and replicate in simulations. The ejected mass can form a shell around the star we consider the circumstellar material (CSM). In this study, we use ALMA interferometric observations to find the structure of Betelgeuse's CSM, and connect to the mass loss mechanisms that could form it. We measure a bipolar circumstellar structure with a position angle of 42.3$\pm 7.0^\circ$. We observe asymmetries in the form of hot spots in the north east of both the stellar surface and CSM. The CSM intensity peaks at 0.0716 Jy arc$^{-2}$ = 2.4483 mJy beam$^{-1}$, with a surface dust density of $2.4578 \times 10^{-4}$ g cm$^{-2}$. The total volumetric density of the CSM ranges from $\approx 10^{-16}$ to $10^{-14} \ \text{g cm}^{-3}$, with a total CSM mass $\sim5 \times10^{-4} - 1.5 \times 10^{-3} M_\odot$. The resulting density distribution could not be formed with a steady state wind, suggesting mass loss on Betelgeuse is not constant. This work motivates studies of the circumstellar density distribution of massive stars, growing our understanding of stellar atmospheric dynamics and mass loss.

Download

Share

COinS