Astronomy and Astrophysics, volume 300, 923-932 (1995/8-3)
The S 140/L 1204 complex: radio recombination lines of hydrogen, carbon and sulphur.
SMIRNOV G.T., SOROCHENKO R.L. and WALMSLEY C.M.
Abstract (from CDS):
We have used the Effelsberg 100-m telescope to observe the hydrogen and carbon 165α and 166α radio recombination lines towards the S 140/L 1204 complex. In addition to the transitions known from earlier observations, we detect a feature due to ionized sulphur. On the basis of the observed H line parameters, we conclude that the emission nebula S 140 is only a part of a larger partially obscured H II region which has an electron temperature of 6400K and an electron density of order 10cm–3. The obscured fraction of the H II region appears to be either behind or partially immersed in the molecular and C II regions. We derive parameters for the C II region by combining our results with measurements of the C II 158µm fine structure line by Boreiko et al. (1990) and conclude that the temperature is in the range 75-200K whereas the electron density is in the range 0.5-9cm–3. If there is pressure equilibrium between H II and C II gas, then the lower values of the temperature and density are preferable.
ISM: atoms - ISM: clouds - ISM: H II regions - ISM: individual objects: S 140 (SH 2-140) - ISM: individual objects: L 1204 (LDN 1204) - radio lines: interstellar