A correlation of H2 regions with H1 gas and the rate of star formation in galaxies

A correlation analysis is made between the distributions of H2 regions and neutral hydrogen in seven galaxies, LMC, SMC, M31, NGC2403, M101, M51, and NGC6946. A dependence of the rate of star formation R on the gas density is derived. Regardless of the morphological type of galaxies the relation obtained agrees with the form employed by Schmidt (1959), R proportional to rho. A detailed analysis is made of the distribution of H2 regions in the LMC and it is found that the H2 regions have a tendency to form a clustering which cannot be explained only by the irregular distribution of H1 gas. This suggests the presence of another factor for the rate of star formation besides the gas density. (auth.)