Journal article

The Hubble Space Telescope key project on the extragalactic distance scale. XV. A Cepheid distance to the Fornax Cluster and its implications

BF Madore, WL Freedman, N Silbermann, P Harding, J Huchra, JR Mould, JA Graham, L Ferrarese, BK Gibson, M Han, JG Hoessel, SM Hughes, GD Illingworth, R Phelps, S Sakai, P Stetson

The Astrophysical Journal | Published : 1999


Using the Hubble Space Telescope, 37 long-period Cepheid variables have been discovered in the Fornax Cluster spiral galaxy NGC 1365. The resulting V and I period-luminosity relations yield a true distance modulus of μ0 = 31.35 ± 0.07 mag, which corresponds to a distance of 18.6 ± 0.6 Mpc. This measurement provides several routes for estimating the Hubble constant. (1) Assuming this distance for the Fornax Cluster as a whole yields a local Hubble constant of 70 ± 18 (random) ± 7 (systematic) km s-1 Mpc-1. (2) Nine Cepheid-based distances to groups of galaxies out to and including the Fornax and Virgo Clusters yield H0 = 73 ± 16 (random) ± 7 (systematic) km s-1. Mpc-1. (3) Recalibrating the I..

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