SIMBAD references

We report the first results of a long-term programme aiming to provide accurate independent estimates of the Hubble constant (H₀) using the L(Hβ)–σ distance estimator for giant extragalactic H II regions (GEHR) and H II galaxies.

We have used Very Large Telescope and Subaru high-dispersion spectroscopic observations of a local sample of H II galaxies, identified in the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) catalogue in order to redefine and improve the L(Hβ)–σ distance indicator and to determine the Hubble constant. To this end, we utilized as local calibration or `anchor' of this correlation GEHR in nearby galaxies which have accurate distance measurements determined via primary indicators. Using our best sample of 69 nearby H II galaxies and 23 GEHR in nine galaxies, we obtain H₀= 74.3 ± :.1 (statistical)±2.9 (systematic) km/s.M/pc, in excellent agreement with, and independently confirming, the most recent Type Ia supernovae based results.