H I and optical observations of dwarf galaxies

H I observations have been made with the 76-m Lovell Telescope of 36 galaxies of the blue compact and the low surface brightness type, of which 23 are true dwarfs ($$M_B\geqslant-16$$ mag) and 31 have optical diameters less than 10 kpc. Photoelectric photometry from the Kitt Peak 2.1-m telescope reveals systematic errors in previous studies. The observations confirm the relative hydrogen richness of dwarf galaxies and indicate an increase in gas richness with decreasing luminosity. The distribution of intrinsic dwarf galaxy shapes is derived and applied to the statistical calculation of dwarf galaxy total masses, taking into account support by internal pressure. The contribution of dwarf galaxies to the total luminosity density in the nearby Universe is ∼ 10 per cent and their H I contribution is ∼ 30 per cent.