Spectral Evolution Models for the Next Decade
  Spectral evolution models are a widely used tool for determining the stellar
content of galaxies. I provide a review of the latest developments in stellar
atmosphere and evolution models, with an emphasis on massive stars. In contrast
to the situation for low- and intermediate mass stars, the current main
challenge for spectral synthesis models are the uncertainties and rapid
revision of current stellar evolution models. Spectral libraries, in particular
those drawn from theoretical model atmospheres for hot stars, are relatively
mature and can complement empirical templates for larger parameter space
coverage. I introduce a new ultraviolet spectral library based on theoretical
radiation-hydrodynamic atmospheres for hot massive stars. Application of this
library to star-forming galaxies at high redshift, i.e., Lyman-break galaxies,
will provide new insights into the abundances, initial mass function and ages
of stars in the very early universe.
