Blue Supergiants - Starway to Virgo and Fornax

Abstract.

The mechanical momenta contained in the radiation driven winds of Blue Supergiants are tightly correlated with stellar luminosities. This Wind Momentum - Luminosity Relationship provides a unique opportunity to determine extragalactic distances by purely spectroscopic means unaffected by uncertainties in reddening and metallicity. Extrapolating from most recent work on Blue Supergiants in Local Group galaxies it is concluded that with medium resolution, multi-object spectroscopy carried out at 8m class telescopes (for instance FORS at the VLT) distance moduli of spiral and irregular galaxies can be obtained with an accuracy of 0.1 mag out to the Virgo and Fornax clusters of galaxies.