Distinguish the low- and intermediate-hydrogen models of AF And

Determine whether the low-hydrogen model with a hydrogen mass fraction of 20 percent or the intermediate-hydrogen model with a hydrogen mass fraction of 30 percent more accurately represents the observed spectrum of AF And.

Background

The authors construct separate cmfgen atmosphere models for AF And with hydrogen mass fractions of 20, 30, and 40 percent. The high-hydrogen model is disfavoured because it cannot simultaneously reproduce the observed hydrogen, helium, silicon, and iron line intensities.

Both the 20-percent and 30-percent models reproduce the observed spectrum with acceptable quality, but they require different mass-loss rates and yield different current stellar masses in the subsequent dynamically consistent modelling. The available optical spectra therefore do not resolve which of these two hydrogen abundances is preferred.