Star formation in thin disks of spiral galaxies seen face-on
  Estimates of the integrated (SFR) and specific (sSFR) rates of star formation
are given for 181 galaxies of later Sc, Scd, and Sd types seen almost face-on.
Their SFRs were determined from FUV fluxes in the GALEX survey. The median
values of the sSFR are: -10.66 dex for Sc, -10.44 dex for Scd, and -10.40 dex
for Sd types in units of yr-1. The average value of the sSFR for these galaxies
falls off smoothly from lowmass to giant disks. After accounting for
photometric errors, the specific star formation rate has a small cosmic
variation of 0.16 dex. In order to reproduce the observed stellar mass on a
cosmic time of 13.8 Gyr, the galaxies without bulges viewed face-on must have
had an SFR two-three times higher in the past than observed now.
