A new method of determining distances to galaxies

Tully, R.B. & Fisher, J.R. 1977, Astr. Ap. 54, 661.

It is proposed that for spiral galaxies there is a good correlation between the global neutral hydrogen line profile width, a distance-independent observable, and the absolute magnitude (or diameter). Such a relation is first sought in nearby calibration galaxies of the Local Group, the M 81 group, and the M 101 group, with well-determined distances, accurately known photometric properties, and accurately known global hydrogen profile width. On the basis of these calibration magnitude-global profile width and diameter-global profile width relationships, distances were derived for the Virgo cluster and the Ursa Major cluster. The distance moduli obtained are 30.6 m for the Virgo cluster and 30.5 m for the Ursa Major cluster. The result for the Virgo cluster suggests a Hubble constant of 80 km per sec per Mpc.