Molecular clouds and star formation in galaxies in the local universe

The observations made as a part of the FCRAO Extragalactic CO Survey are used to examine the molecular gas distributions, the global H-2 masses, the star formation efficiency, the H-2/H I ratio, and the gas to dust ratio, within and among 300 galaxies in the local universe as a function of morphology, luminosity, and environment. Significant global trends in the gas-to-dynamical mass ratio, the molecular gas-to-warm dust mass ratio, and the H-2/H I ratio are found as a function of morphology for spiral galaxies along the Hubble sequence. Globally in these systems, the luminosity of high mass stars per unit mass of molecular gas (also called the star formation efficiency) does not vary in the mean as a function of morphology, while the star formation efficiency does show significant variations as a function of environment. The star formation efficiency also shows a marked tendency to be elevated in smaller galaxies. All of these results are discussed, and used to provide insight into the processes of star formation and galaxy evolution, as well as placing constraints on current models of galaxy evolution.