GALACTOCENTRIC-DISTANCE DEPENDENCE OF MOL ECULAR CLOUD CORE DENSITY

Results of observations of the (CO)-O-18 J = 1 - 0 and J = 2 - 1 lines toward 28 HII regions are presented. The observations were carried ou t on the 12-meter telescope of NRAO, USA. The J = 1 - 0 line was detec ted in 24 objects, for 20 of them emission peak positions and angular sizes were determined. The data obtained are compared with observation s of the same objects in the CO J = 1 - 0 line, We found considerable influence of dilution, apparently due to clouds' fragmentation. In S20 1 we detected an anomalously intense (CO)-O-18 J = 2-1 line. For the r est 11 objects the equation of radiative transfer was solved, molecula r cloud cores' masses and densities were determined. Mean Hz concentra tion is 4 x 10(3) cm(-3). Within the errors of observations, the H-2 c oncentration can be considered as constant within the galactocentric d istance interval of 4 - 14 kpc, Core sizes are between 0.3 and 5.5 pc, and their masses - (2.3 - 7.8) x 10(3) M.. Cores with sizes > 1 pc ar e probably subject to contraction. The dependence of the (CO)-O-18 J = 1 - 0 linewidth on the core size fits rather well the Kolmogorov subs onic turbulence law.