CO detections and IRAS observations of bright radio spiral galaxies at cz< or =9000 kilometers per second

CO emission has been detected from 20 of 21 bright radio spirals with strong extended nuclear sources, including the most distant (NGC 7674) and the most luminous (IC 4553 = Arp 220, NGC 6240) galaxies yet detected in CO. All of these galaxies are rich in molecular gas, with M/sub total/(H2) = 3 x 108-2 x 1010 M. IRAS observations show that they have a strong far-infrared (FIR) excess, with L/sub FIR//L/sub B/roughly-equal 1-35 and L/sub FIR/(40-400 μm) roughly-equal 1010-1012 L. The primary luminosity source for these radio cores appears to be star formation in molecular clouds. A strong correlation is found between the FIR and extended 21 cm continuum flux, implying that the fraction of massive stars formed is independent of the star formation rate. The ratio L/sub FIR//M(H2) provides a measure of the current rate of star formation, which is found to be a factor 3-20 larger in these galaxies than for the ensemble of molecular clouds in the Milky Way. At these rates their molecular gas will be depleted in approx.108 yr