Emission from O2 Gas in the Kleinman-Low Region of the Great Nebula in Orion

Abstract

EMISSION FROM O2 GAS IN THE KLEINMAN-LOW REGION OF THE GREAT NEBULA IN ORION by Michael D. Turner We calculated line intensities of ground-state emission from atomic ([O I]) and molecular (O2) oxygen under various conditions of temperature (10–10 4 K) and density (10–10 cm−3) in photodissociation regions (PDR) of molecular gas clouds, with UV flux intensity (G0) of 10 . 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 (10 –10 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.