Multifrequency Studies of Massive Cores with Complex Spatial and Kinematic Structures

Five regions of massive-star formation have been observed in various molecular lines in the frequency range similar to 85-89 GHz. The studied regions comprise dense cores, which host young stellar objects. The physical parameters of the cores are estimated, including the kinetic temperatures (similar to 20-40 K), the sizes of the emitting regions (similar to 0.1-0.6 pc), and the virial masses (similar to 40-500 M-circle dot). The column densities and abundances of various molecules are calculated assuming Local Thermodynamical Equilibrium(LTE). The core in 99.982+4.17, which is associated with the weakest IRAS source, is characterized by reduced molecular abundances. The molecular line widths decrease with increasing distance from the core centers (b). For b greater than or similar to 0.1 pc, the dependences Delta V (b) are close to power laws (alpha b(-p)), where p varies from similar to 0.2 to similar to 0.5, depending on the object. In four cores, the asymmetries of the optically thick HCN(1-0) and HCO+(1-0) lines indicates systematic motions along the line of sight: collapse in two cores and expansion in two others. Approximate estimates of the accretion rates in the collapsing cores indicate that the forming stars have masses exceeding the solar mass.