ELT Spectroscopy of Extragalactic Massive Stars
  Quantitative spectroscopy of O-type stars in galaxies beyond 1 Mpc requires
the unprecedented sensitivity of the so-called Extremely Large Telescopes.
Visible spectroscopy with these exciting new facilities will give us the first
chance to explore the properties of large samples of massive stars in very
metal-poor galaxies, as well as the broad range of environments in the galaxies
of the Sculptor Group and beyond. In this context, we introduce performance
simulations of visible spectroscopy of extragalactic massive stars with the
MOSAIC instrument, which is a multi-object spectrograph in development for the
European Extremely Large Telescope (ELT). Preliminary results demonstrate that
we can obtain sufficient signal-to-noise from one night of observations in
galaxies out to distances of 3 to 4 Mpc (V = 22-23 mag). We also highlight the
goal of obtaining ultraviolet spectroscopy of the same individual stars beyond
1 Mpc; this will require a future large-aperture space telescope with UV
capabilities such as the LUVOIR concept currently under study.
