Year of Publication

2010

Degree Name

Doctor of Philosophy (PhD)

Document Type

Dissertation

College

Arts and Sciences

Department

Physics and Astronomy

First Advisor

Doctor Thomas Troland

Abstract

This document describes studies of two independent regions of the interstellar medium (ISM). These studies have the common element that both pertain to regions in our Galaxy that are known to be associated with present-day star formation. These studies aim to help us understand the ISM, star formation, and ultimately where we came from, since, after all, our star, the Sun, is itself the product of star formation 4.5 billion years ago. The first project measured the Zeeman Effect on the 21 cm H I absorption line in order to create a map of the line of sight magnetic fields near a star forming region called W3. From the map of the field, it was possible to create a three dimensional model of the magnetic field morphology. Also, calculating the various energies associated with W3 revealed that it is most likely in virial equilibrium, not expanding or contracting.

The second project used an instrument on the Hubble Space Telescope (HST) to measure the abundance of iron in a neutral region near the Orion Nebula called Orion’s Veil. One of the goals of this project is to investigate whether solid dust grains can be destroyed by ionizing radiation by comparing the amount of solid iron in Orion’s Veil to the amount in the nearby ionized regions. By measuring the depletion of iron in the neutral Veil and comparing it to the depletion of iron the H+ regions of the Orion Nebula, it was possible to conclude that iron was not being released into the gas phase by ultraviolet photons. In addition, oscillator strengths for two Fe II transitions were measured.

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