  We have shown that in the atmosphere of SN 1987A level populations of
hydrogen are mostly controlled by an ionization freeze-out and ion-molecular
processes up to 40 days. The ionization freeze-out effects are important for
normal SNe II-P as well. The time dependent effects and the mutual
neutralization between H^- and H^+ may result in a non-monotonic radial
dependence of the Sobolev optical depth for H-alpha and then in a blue emission
satellite of H-alpha observed in SN 1987A spectra at Bochum event phase. The
relative abundance of molecular hydrogen about 0.0001-0.001 is high enough for
the photospheric phase of SN 1987A. We emphasize that the poor knowledge of the
far UV radiation field in the envelope of SN 1987A still forbids a truly
reliable estimate of the Ba abundance but well-constructed and tested models
may improve this situation.

Astrophysics