| Abstract | Systematic observations in the 21 cm line of neutral hydrogen with the Nancay radiotelescope have detected 392 spiral galaxies of type Sb or later, and 172 neutral hydrogen fluxes have been obtained. A mean value of each global parameter has been determined for each morphological type, and the internal dispersion of values has been analyzed. Dispersion for all parameters is reduced when the distance scale determined by de Vaucouleurs is used, instead of assuming constant Hubble flow. Part of this internal dispersion is intrinsic, related to the relation of the galaxies to their neighborhood, and is reduced by eliminating galaxies with nearby companions. Isolated galaxies seem to have a larger ratio of neutral hydrogen mass to luminosity, and so could have a larger neutral hydrogen content. |
