Xb. Lin et al., SN 1987A - EVOLUTION OF THE ENVELOPE TEMPERATURE AS DEDUCED FROM H-ALPHA EMISSION, The Astrophysical journal, 494(2), 1998, pp. 806-811
In this paper, we present a new method for determining the temperature
and ionization evolution of the hydrogen envelope of SN 1987A by comp
aring the observed H alpha light curve and one which is derived from t
he recombination theory for hydrogen lines, This is a simple and conve
nient method for determining the temperature and ionization evolution
which could be applicable to the late time of all Type II supernovae.