Cometary outbursts - a search for a cause of the comet 17P/Holmes outburst

Abstract

Periodic comet 17P/Holmes underwent a very large outburst of brightness on 2007 October 24. In this paper, the probable causes of this event have been reviewed. Consideration focuses on the four potential mechanisms as follows: (a) the polymerization of hydrogen cyanide HCN; (b) the crystallization of amorphous water ice; (c) thermal stresses and (d) stresses created by icebound CO. The main characteristics of cometary outbursts have been calculated and discussed as the values of released energy and jumps of brightness caused by the considered mechanisms. The obtained results are consistent with the ones observed during the outburst of comet 17P/Holmes. The main conclusion of this paper is as follows. The hypothesis concerning the stresses related to CO inclusions appears to be the most probable cause of the comet 17P/Holmes outburst according to our present knowledge about the physical and chemical structure of comets.