Publication Date

Spring 2012

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

Advisor

Michael J. Kaufman

Keywords

astrochemistry, Interstellar medium, Orion-KL nebula, star formation, submillimeter emission

Subject Areas

Astrophysics

Abstract

We calculated line intensities of ground-state emission from atomic ([O I]) and molecular (O2) oxygen under various conditions of temperature (10–104 K) and density (10–104 cm-3) in photodissociation regions (PDR) of molecular gas clouds, with UV flux intensity (G0) of 105. Using a magnetohydrodynamic shock model to produce profile data in a range of pre-shock velocities (5 ≤ vs ≤ 20 km s-1) and a range of pre-shock H and H2 gas densities (103–105 cm-3), we calculated line intensities for both [O I] and O2 emission. Finally, we used these tools successfully to find a model that best describes the recent observations made by the Herschel Oxygen Project team of the 487 GHz, 774GHz, and 1121 GHz lines of O2 in the Kleinman-Low region of the Great Nebula in Orion. Assuming that the source fills all the beams, our calculated 1121/774 intensity ratio falls well outside the statistical uncertainty limits of the observed ratio. Alternatively, assuming that the source fills the 1121 GHz beam, but not the 774 GHz and 487 GHz beams, we found source diameters which produce ratios equal to the mean values for the observed beam ratios.

Download

Share

COinS