  We present a new model of the optical nebular emission from HII regions by
combin- ing the results of the Binary Population and Spectral Synthesis (bpass)
code with the photoion- ization code cloudy (Ferland et al. 1998). We explore a
variety of emission-line diagnostics of these star-forming HII regions and
examine the effects of metallicity and interacting binary evo- lution on the
nebula emission-line production. We compare the line emission properties of HII
regions with model stellar populations, and provide new constraints on their
stellar populations and supernova progenitors. We find that models including
massive binary stars can successfully match all the observational constraints
and provide reasonable age and mass estimation of the HII regions and supernova
progenitors.
