NEAR-INFRARED SPECTRA OF SN-1987A - DAYS 936 TO 1445

We present 1-2.5 μm spectra of SN 1987A taken 936, 1058, 1109, 1294, and 1445 days after core collapse. The low resolution (λ/Δλ≈150) spectra show many lines from neutral and singly ionized species, most notably Fe and Si. We also tentatively detect Co emission. Measurements of several [Fe II] lines suggest that on day 936 the electron density in the Fe II emitting region was 104.0±0.3 cm-3. This density and the intensity of the [Fe II] lines suggest that the electron temperature on day 936 was between 1900 and 3000 K. We find that the electron temperature throughout these epochs is greater than ∼1500 K, which seems to indicate that the Fe escaped an infrared catastrophe through day ∼1500. The total mass of Fe estimated from our measurements is less than 0.04 Script M sign⊙, most of which if Fe0 and lower than many theoretical expectations. We also show that the Fe II and the observed H I emission lines probably come from different regions in the ejecta of the supernova.