Outbursts of comets—the case of 1P/Halley

Possible mechanisms that were the reason of the unexpected strong outburst of 1P/Halley observed on February 12, 1991 at 14.3 AU heliocentric distance have been considered. As a plausible mechanism, a combination of the polymerization of HCN with the amorphous water–ice transformation has been proposed. Probably, the electrostatic destruction of cometary grains in the cometary coma also took place. Calculations have been carried out for a large range of cometary parameters and it has been shown that the proposed scenario of the outburst gives a jump in the comet brightness which is consistent with the real jump observed during the 1P/Halley outburst.