On the possibility of dust condensation in the ejecta of supernova 1987a.

We suggest that supernova 1987a may condense dust of substantial visual optical thickness as do many novae. The dust will act as a calorimeter of the photon luminosity of any central engine that is dominant at the time of dust formation. Observations of novae suggest that dust formation may occur when the expanding ejecta reach a temperature of 1000 K. The early luminosity of the supernova may be dominated by radioactivity that is unrelated to the central engine that determines the energy balance for the long-term development of the supernova. We discuss the possibility that a constant luminosity central power source such as a pulsar dominates the luminosity of the supernova ejecta by the time that dust can condense and argue that, if a shell mass of more than a few tenths of one solar mass was ejected, emission from dust may be observable in the thermal infrared spectral region. Maximum dust optical depth should occur by late 1987 or early 1988. If the dust becomes optically thick, the visual light from the supernova may drop precipitously. The characteristics of an optically thick dust shell as a calorimeter of the luminosity of the central engine are discussed and are related to previous observations of dust formation in type II supernovae. It is suggested that dust of several chemical compositions may form at different epochs.