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Better Parallaxes and the Cosmic Distance Scale

Published online by Cambridge University Press:  07 August 2017

Sidney Van Den Bergh*
Affiliation:
Dominion Astrophysical Observatory 5071 West Saanich Road Victoria, B.C., V8X 4M6 Canada

Abstract

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It is generally agreed that the Hubble parameter lies in the range 50 < Ho (km s−1 Mpc−1) < 100. Recent observations, which are discussed in the present paper, favor Ho ≳ 75 km s−1 Mpc−1. Hubble Space Telescope observations of Cepheids in Virgo cluster galaxies will probably reduce the uncertainty in Ho to ∼ 20%. It should be possible to lower this remaining uncertainty in the Hubble parameter by strengthening the calibration of the Cepheid period-luminosity relation, the MV(RR) versus [Fe/H] relation of RR Lyrae stars, and the luminosity calibration of the subdwarf main sequence, by using parallaxes obtained with Hipparcos.

Type
2. Current and Future Needs for Very Accurate Astrometry
Copyright
Copyright © Kluwer 1995 

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