Probing supernovae ejecta by Halpha damping wings

It is predicted that H$\alpha$ emission line at the early nebular epoch of type II-P supernovae may display robust observational effects of damping wings. This is illustrated by Monte-Carlo simulations. The strength of damping wing effects may be used to constrain parameters of the line-emitting zone. An anomalous redshift, width and red wing of H$\alpha$ revealed by SN 1997D on day 150 are explained in terms of damping wing effects.