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Determination of physical parameters of NGC 2023 using the hyperfine NH3 spectrum |
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| Authors: | Xing Jun Xu Lan-Ping |
| Institution: | aDepartment of Geophysics, Beijing University, China |
| Abstract: | An improved approach is given for deriving the physical parameters of a molecular cloud by its NH3 rotation-inversion hyperfine spectra. The optical depth τ0(1, 1) of NH3 (1,1) is obtained by considering the blending effect of the magnetic hyperfine spectral lines, the (1-1) excitation temperature Tex (1, 1) is calculated by a two level model, the effect of different collision rate and the thermalization of the (1, 1) inversion lines are discussed, the rotation temperature TR ( 2, 1) between the NH3 levels (2, 2) and (1, 1) and the column density N( 1, 1) of the NH3 (1, 1) inversion level are derived, the results of the total column density from different assumptions for the abundance ratio of ortho-NH3 and para-NH3 are also discussed. This approach is used for the molecular cloud NGC 2023 by using the relevant observed data and its optical depth and other physical parameters are obtained. |
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