Date of Award

8-1-2011

Document Type

Masters Thesis

Degree Name

M.S.

Organizational Unit

College of Natual Science and Mathematics

First Advisor

Toshiya Ueta, Ph.D.

Second Advisor

Robert Stencel

Third Advisor

Jennifer Hoffman

Keywords

Mass loss, Asymptotic Giant Branch stars, Spatial distribution

Abstract

We provide high-resolution maps of the circumstellar dust shells of several dozen Asymptotic Giant Branch (AGB) stars using data from the Spitzer space telescope Multiband Imaging Photometer (MIPS) imaged at 70µm. AGB stars are the major contributors of chemical elements such as carbon, oxygen and silicon, which are essential to the existence of life in the universe, through mass loss processes that take place at the surface of the star. We probe the spatial distribution of cold (~40 K) dust grains in order to trace the history of mass loss from the observed radial density variation in these shells. Our images illustrate that different morphologies may evolve because AGB stars can already interact with the interstellar medium (ISM) that surrounds them even at these early stages of the AGB mass loss history. Relative motion of the star as well as the ISM with respect to the local environment may be of particular importance for shell structure evolution.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Kathleen M. Geise

Provenance

Received from ProQuest

File Format

application/pdf

Language

en

File Size

169 p.

Discipline

Astrophysics

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