Constraints on the Hubble constant from observations of the brightest red-giant stars in a Virgo-cluster galaxy

The nearest large groups of elliptical galaxies, in the Virgo and Fornax clusters, play a central role in determinations of the Hubble constant, H0, and hence the cosmological rate of expansion. Because the relative distances between these two clusters and more remote clusters are well known, absolute distance determinations to Virgo and Fornax should establish the Hubble constant for the local Universe. In addition, elliptical galaxies reside …