FUV Spectroscopy of Interstellar and Circumstellar Materials

Graduate Thesis Or Dissertation

Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/0p096699j

Abstract

I have designed, assembled, and calibrated a sounding rocket payload to perform high-resolution FUV spectroscopy. Debate lingers over the existence of a pervasive 1 million K gas in our region of the interstellar medium, the Local Bubble. If this hot gas were present, it would produce O VI upon interacting with the cold cavity wall. As such, O VI serves as a diagnostic for the hot interstellar gas. I designed the Diffuse Interstellar Cloud Experiment (DICE) to measure the O VI (1032,1038 Angstrom) doublet in absorption against two stars on either side of the Local Bubble wall. The instrument is functionally a Cassegrain telescope followed by a modified Rowland-mount spectrograph. With a holographically-ruled grating and a secondary magnifying optic, the spectrograph can achieve high resolving power (R=60,000) in a compact space. In addition, I have analyzed Carbon Monoxide (CO) emission from Classical T-Tauri star disks using spectra from the HST-Cosmic Origins Spectrograph. The CO is photo-excited by Lyman alpha from the magnetospheric shock. I model this incident Lyman alpha radiation to use as input for a simple CO fluorescence model. Fits to the data constrain CO temperatures and column densities, which can then be compared with other known properties of the disks in our target sample. I find no correlation between this UV-emitting CO and the CO studied at infrared and sub-mm wavelengths between targets.

Creator