Molecules in the ejecta of SN 1987A

Carbon monoxide has been observed in the ejecta of SN 1987A. The molecular formation and destruction mechanisms in the ejecta environment are explored to determine how the CO and other molecules may be formed. In the absence of grains the first molecules must be formed either through negative ion reactions or through radiative association. The molecules are destroyed by interactions with the radiation field, by fast electron impact, and most effectively by charge transfer reactions with He(+) ions. The CO masses inferred from the observations of vibrational emission can be reproduced by a partially mixed model of the element distribution or by a fully mixed model with rapid charge transfer of He(+) to metal atoms. 23 refs