| Abstract | H-alpha photometry is presented for the brightest H II regions in 21 Virgo cluster Sc galaxies. Fitting these data to the calibration data for Local and M81 group galaxies yields a true distance modulus to the Virgo cluster of 31.4 + or - 0.25 magnitudes, based on the Sandage and Tammann local distance scale, but independent of their distance to the M101 group. The Virgo H II regions appear to possess a very large dispersion in H II region properties, even among galaxies of the same type. Observational errors and selection effects cannot account for this scatter, and it is argued that it is real. If the dispersion is representative of field galaxies, distances derived to individual galaxies using H II regions will be subject to large random errors, and other methods should be used instead. |
