Volume 541, May 2012
|Number of page(s)||5|
|Published online||24 May 2012|
The frequencies, upper energy levels, upper level degeneracies, and Einstein coefficients of the observed transitions were taken from the JPL spectroscopic database (Pickett et al. 1998) and are summed up here in Table A.1.
Parameters of detected lines.
The column densities were determined within the LTE approximation, using (B.1)where ν is the frequency of the transition, c the velocity of light, h and k the Planck and Boltzman constants, respectively, gup the upper level degeneracy, Aul the spontaneous emission Einstein coefficient, Tex the excitation temperature, Q(Tex) the partition function at Tex, Eup the upper level energy, and Jν(T) is the radiation temperature that is defined as (B.2)Equation (B.1) assumes that the lines are optically thin. We note that since the temperatures are very low, Jν(Tbg) is not negligible with respect to Jν(Tex).
© ESO, 2012
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