No CrossRef data available.
Published online by Cambridge University Press: 14 August 2015
The use of the brightest members of galaxy clusters as distance indicators is questioned because of a possible correlation between the absolute magnitude of the brightest galaxy and the richness of the cluster. Comparison of the clusters' luminosity functions is considered to be more appropriate. The difference between the two approaches is substantial when a comparison is made between the Coma and Virgo clusters. The value of the Hubble parameter may well be less than 50 km s−1 Mpc−1.