Jim McCarthy
CalTech
            Studies of Blue Supergiant Stars in External Galaxies
                          with the Keck Telescopes

The advent of 10m class telescopes enables one to study the visually
brightest stars in Local Group galaxies at high resolution and high
signal-to-noise ratio, as previously possible only for stars in our
own Galaxy and the Magellanic Clouds.  McCarthy and collaborators have
undertaken Keck-I HIRES spectroscopy of A- and B-type supergiants in 
M31 and M33.  This talk will demonstrate that detailed chemical element
abundances can be derived from the HIRES spectra, which will enable us
to determine the abundance gradients as a function of galactocentric
distance in these galaxies.  Furthermore, analysis of the H-alpha line
profile permits us to determine the momentum in the stellar wind, a 
potential new distance indicator via the Wind-Momemtum -- Luminosity
Relation.  The HIRES data are being used to test this method.