Star formation properties of spiral galaxies

The gas properties of barred and unbarredspiral galaxies are compared in two complete samples.It is found that two types of spiral galaxies do notdiffer to each other in atomic and molecular gascontents. On average there is 6 times more HI thanH2 in spiral galaxies and the ratio MHI/MH2decreases from early to late types. The barred andunbarred spirals in general show a similar behaviorsof the gas-to-luminosity relationships, but also thereare certain differences between them such ascorrelation of two gas phases (HI and H2) forunbarred galaxies. It is suggested that differentbehaviors of two types galaxies are due to the higherstar forming activity of barred with respect unbarredspirals. The expected values of HI and H2 gascontents have been estimated using blue and far-infrared emission.