Dense cores of interstellar molecular gas

Abstract

From the analysis of real observation data concerning the (J;K) = (1; 1) and (J;K) = (2; 2) inversion transitions of the ammonia molecule, I estimated the physical parameters for the molecular cloud L1228. First of all, I identi ed the lines of interest in twelve di erent spectra, measured in a twelve-point grid which also allowed me to outline a map of the dense region. Secondly, by means of the maximum intensity and the FWHM of the transition lines, after being tted to a gaussian distribution, I characterized the (J;K) = (1; 1) transition by the optical depth and the excitation temperature. Lastly, I found some important properties of the condensation such as its size, the kinetic temperature and the column and volume densities leading to two di erent values of the mass whose discrepancy con rmed that the region is not optically thin. Comparing my results for the clump mass with the virial mass, I was able to state the approximate equilibrium of the dense core of L1228.