EVIDENCE FOR ENERGIZING OF H-ALPHA EMISSION IN TYPE-II SUPERNOVAE BY EJECTA WIND INTERACTION

A simple one-zone model of H-alpha luminosity of late time type II supernovae (t > 100 d), energized by Co-56-Fe-56 decay, was applied to the analysis of the observed H-alpha evolution. Of the six available SNeII with known H-alpha fluxes at late times, three reveal the extra H-alpha flux above the radioactive model. This excess is interpreted as an effect of an energy release due to ejecta-wind interaction. Two SNeII, 1979C and 1987F, with the particularly strong H-alpha excess, show additional spectroscopic signatures, which can be attributed to the dense wind around supernovae. In SN 1987F the wind density parameter M/u(w) is of the order of 10(17) g cm-1, thus being high enough to provide a noticeable contribution arising from ejecta-wind interaction to the overall optical luminosity at late times (t > 150 d). The hard X-ray (kT approximately 50 keV) luminosity of the outer shock wave must have been, in this case, of the order of 10(42) erg s-1 at 150 d. The modelling of the H-alpha profile in SN 1987F at t = 150 d provides compelling evidence in favour of the existence of an inner radiative shock wave.