Cometary impacts with the sun - Physical and dynamical considerations

Abstract

Michels et al. (1982) observed the apparent impacting of the sun by a comet, and Sekanina (1982) showed that the comet, 1979XI, was probably a member of the Kreutz group of sun-grazing comets, although its perihelion of 0.35 solar radii was much smaller than the 1.2-1.9 solar radii common for this comet class. The perihelion change cannot be explained by planetary, stellar, or nongravitational perturbations. The most plausible explanation is collision with another body, probably a comet, at large heliocentric distance. The probability of such an event is, however, extremely small. The sublimation of the comet's nucleus before impact is discussed, and it is suggested that its ultimate destruction probably resulted from the shock of entry into the denser regions of the solar atmosphere, just above the photosphere.