PHYSICAL PROPERTIES AND KINEMATICS OF DENSE CORES ASSOCIATED WITH REGIONS OF MASSIVE STAR FORMATION FROM THE SOUTHERN SKY

The results of spectral observations in the $\sim 84-92$ GHz frequency range of six objects from the southern sky having dense cores and associated with massive star and star cluster forming regions are presented. The observations are carried out with the MOPRA-22m radio telescope. Within the framework of the local thermodynamic equilibrium (LTE) approximation, column densities and abundances of the H¹³CN, H¹³CO⁺, HN¹³C, HC₃N, c-C₃H₂, SiO, CH₃C₂H and CH₃CN molecules are calculated. Kinetic temperatures ($\sim 30-50$ K), sizes of emission regions ($\sim 0.2-3.1$ pc) and virial mass esimates ($\sim 70-4600M_{\odot }$) are obtained. The linewidths in the three cores decrease with increasing distance from the center. Four cores exhibit asymmetry in the profiles of the optically thick HCO⁺(1–0) and HCN(1–0) lines, indicating the presence of systematic motions in the line of sight. In two cases, the asymmetry can be caused by contraction of gas. The model HCO⁺(1–0) and H¹³CO⁺(1–0) spectral maps obtained within the non-LTE spherically symmetric model are fitted into observed ones. Radial density ($\propto r^{-1.6}$), turbulent velocity ($\propto r^{-0.2}$) and contraction velocity ($\propto r^{0.5}$) profiles in the G268.42–0.85 core are obtained. The contraction velocity radial profile differs from expected both in the case of free fall of gas onto a protostar ($r^{-0.5}$), and in the case of global core collapse (contraction velocity does not depend on distance). A discussion of the results obtained is provided.