A Spectroscopic Study of Blue Supergiant Stars in Local Group Spiral Galaxies: Andromeda and Triangulum

Low-resolution LAMOST and Keck spectra of blue supergiant stars distributed over the disks Local Group spiral galaxies M 31 33 are analyzed to determine stellar effective temperatures, gravities, metallicities, reddening. Logarithmic metallicities at center (in solar units) $0.30\pm0.09$ $0.11\pm0.04$ metallicity gradients $-0.37\pm0.13$ dex/$R_{25}$ $-0.36\pm0.16$ measured for 33, respectively. For 2-dimensional distribution indicates a deviation from azimutal symmetry with an off-centre peak. The flux-weighted gravity-luminosity relationship is used distance modulus 24.51$\pm$0.13 mag 24.93$\pm$0.07 33. gravity--luminosity (FGLR) agrees well other methods. FGLR-based larger than distances Cepheids studies but it in good agreement work on eclipsing binaries, planetary nebulae , long-period variables, tip red giant branch.