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The Large Velocity Approach to H

With the Cepheid distance to Virgo (Freedman et al 1994) a new calibration of the Tully-Fisher relation is available (Mould et al 1995) which allows us to carry distance measurements to 100 Mpc.

 
Figure 1: The velocities of clusters of galaxies in the frame in which the microwave dipole anisotropy vanishes are plotted against the Tully-Fisher distances of these clusters.

Similarly, we can plot the recession velocities of type Ia supernovae from the sample of Tammann & Sandage (1993). We assume that SNeIa are simple standard candles whose apparent visualmagnitude at Virgo is 12.13 0.14 mag.

 
Figure 2: The Hubble flow as seen in the distances of type Ia supernovae. Recession velocities have been corrected for a Virgocentric flow model with an amplitude of 220 km/sec locally.

The () relation provides a second extension of the Population II distance scale to large distances. We show the distances of all the groups tabulated by Faber et al (1985) with more than five members observed. This will be carried out further by the EFAR collaboration.

 
Figure 3: All groups of galaxies studied by the Seven Samurai with more than 5 observed members are shown in a plot of recession velocity versus distance.

The work of Schmidt et al. (1994) now extends to 14,000 km/sec. Cepheid calibrations of host galaxy distances will provide the empirical test of distances from the Expanding Photospheres Method.

 
Figure 4: The Hubble flow as seen in EPM distances (Schmidt et al 1994).

By means of these techniques measurements of H can be freed from the effects of velocity perturbations on the largest scales.



next up previous
Next: The Bubble Model Up: Do we know the velocity field well Previous: The Velocity field



Heron Island Conference
Tue Aug 15 22:04:57 EST 1995