FINITE LIFETIME FRAGMENT MODEL FOR SYNCHRONIC BAND FORMATION IN DUST TAILS OF COMETS

A finite lifetime fragment model is proposed for the formation of synchronic bands in dust tails of comets. Applying the simultaneous fragmentation model proposed by Sekanina and Farrell (1980) to three comets (Mrkos, Seki-Lines, West), we found the lifetime of the fragment to range from 25 to 70 days. On the basis of this result, we propose the following finite lifetime fragment model for synchronic band formation: Parent particles ejected from the nucleus of the comet break up at various times and fragments with a finite lifetime are created. They grow too small to be seen at a certain lifetime. The observed synchronic band is formed by the relatively new fragments and is created within the lifetime. The structure calculated with our theory fits well the observed shape of a synchronic band of Comet West. © 1990.