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Session 68 - Disk Galaxies.
Display session, Wednesday, January 15
Metropolitan Ballroom,
A critical ingredient for modelling galaxy formation and evolution is the parametric relationship between the large-scale star formation rate (SFR) and the physical conditions in the interstellar medium. Most contemporary evolution models still use as their basic SFR `recipe' a simple Schmidt power-law relation between the SFR and gas density, with index n = 1 - 2. The Schmidt law provides an excellent parametrization of the SFR at the high gas densities that are characteristic of active star forming disks, but its empirical form and physical basis are not well understood. This paper presents preliminary results from a new study of the global star formation law in galactic disks, based on new CCD H\alpha observations of an HI/CO-selected sample of nearby galaxies, combined with published data from a variety of sources. The data have been used to investigate the empirical form of the star formation law over a wide range of physical conditions, to test the validity and limits of the Schmidt law approximation, and to investigate the underlying physical basis of the observed relation.
