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Low resolution ESO VLT/FORS spectra of blue supergiant stars are analyzed todetermine stellar metallicities (based on elements such as Fe, Ti, Mg) in theextended disk of the spiral galaxy NGC3621. Mildly subsolar metallicity (-0.30dex) is found for the outer objects beyond 7 kpc independent of galactocentricradius and compatible with the absence of a metallicity gradient confirming theresults of a recent investigation of interstellar medium HII region gas oxygenabundances. The stellar metallicities are slightly higher than those from theHII regions when based on measurements of the weak forbidden auroral oxygenline at 4363 AE but lower than the ones obtained with the R23 strong linemethod. It is shown that the present level of metallicity in the extended diskcannot be the result of chemical evolution over the age of the disk with thepresent rate of in situ star formation. Additional mechanisms must be involved.In addition to metallicity, stellar effective temperatures, gravities,interstellar reddening, and bolometric magnitudes are determined. Afterapplication of individual reddening corrections for each target theflux-weighted gravity-luminosity relationship of blue supergiant stars is usedto obtain a distance modulus of 29.07+/-0.09 mag (distance D=6.52+/-0.28 Mpc).This new distance is discussed in relation to Cepheid and tip of the red giantbranch distances.

Stellar Metallicity of the Extended Disk and Distance of the Spiral Galaxy NGC 3621