Determination of Total C18O Column Density in Orion KL

          @misc{ scivideos_PIRSA:11070050,
            doi = {10.48660/11070050},
            url = {https://pirsa.org/11070050},
            author = {Ahmadi, Aida},
            keywords = {},
            language = {en},
            title = {Determination of Total C18O Column Density in Orion KL},
            publisher = {Perimeter Institute for Theoretical Physics},
            year = {2011},
            month = {jul},
            note = {PIRSA:11070050 see, \url{https://scivideos.org/pirsa/11070050}}
          }
          

Abstract

The large number of high-energy rotational lines of C18O, available via the Herschel Space Observatory, provides an unprecedented ability to model the total C18O column density in hot cores. Using the emission from all the observed lines (up to J=16-15) we use an automated algorithm to model all transitions simultaneously. Under Local Thermodynamic Equilibrium (LTE) assumptions and knowledge of source size, centroid velocity and line width, the model determines the values for total C18O column densities in 4 separate line-of-sight components of Orion KL known as the Extended Ridge, the Outflow/Plateau, the Compact Ridge, and the Hot Core. These values are determined to be: 2.5 X 10^16, 5.9 X 10^16, 1.8 X 10^16, and 6.0 X 10^16 cm^(-2) respectively. We also explain the difficulties in using the said algorithm to model optically thick molecules such as CO which require non-LTE modeling.