H-3(+) EMISSION IN THE EJECTA OF SN 1987A

We present a chemical and thermal model of the envelope of SN 1987A. W e assume that half of the hydrogen envelope is broken into many dense clumps and mixed into the inner region. For a range of densities and e nergy deposition rates, we find two phases, one with a temperature of about 7000 K and another with a temperature of about 3000 K. We sugges t that the H-3(+) features originate in the low-temperature clumps. In them, the cooling is mainly through CO vibrational emission, and the H-3(+) vibrational levels are in LTE. Emission features observed at 3. 41 and 3.53 mu m can be reproduced satisfactorily by H-3(+) fundamenta l band emission at a temperature of 2000 K when absorption by telluric water vapor is taken into account. The model is successful in predict ing the dependence on time of the emission features.