Velocity dispersions in giant H II regions II Relations with the absolute luminosities of the parent galaxies

For pt.I see Astrophys. J., vol.213, no.1, pt.1, p.15-17 (1976). The existence of a close correlation between the linear diameters of giant H II regions in late-type galaxies and the width of their global H/sub alpha / emission is used to establish a close correlation between this width and the absolute magnitudes of the parent galaxies. The relation, calibrated in members of the local and NGC 2403 groups, is used to estimate distance moduli of 26.69/sup m/+or-0.25/sup m/ to NGC 300, and 28.7/sup m/+or-0.6/sup m/ to M101 in good agreement with previous determinations. (21 refs).