Supercatastrophic disruption of asteroids in the context of SOHO comet, fireball and meteor observations

Abstract

Granvik et al. (2016) report an absence of asteroids on orbits with perihelia near the Sun that they attribute to the 'supercatastrophic disruption' of these bodies. Here we investigate whether there is evidence for this process among other bodies with similarly low perihelia: near-Earth asteroids, SOHO comets, as well as meter-sized and millimeter-sized meteoroids. We determine no known near-Earth asteroids have past (last 10^4 years) histories residing significantly inside the Granvik et al. (2016) limit, indirectly supporting the disruption hypothesis. The exception is asteroid (467372) 2004 LG which spent 2500 years within this limit, and thus presents a challenge to that theory. Phaethon has a perihelion distance hovering just above the limit and may be undergoing slow disruption, which may be the source of its dust complex. We find that the rate at which ungrouped SOHO comets are observed is consistent with expected rates for the injection of small (25 m) class asteroids into the near-Sun region and suggest that this fraction of the SOHO-observed comet population may in fact be asteroidal in origin. We also find that there is an absence of meter-sized bodies with near-Sun perihelia but an excess of millimeter-sized meteoroids. This implies that if near-Sun asteroids disrupt, they do not simply fragment into meter-sized chunks but disintegrate ultimately into millimeter-sized particles. We propose that the disruption of near-Sun asteroids as well as the anomalous brightening and destruction processes that affect SOHO comets occur through meteoroid erosion, that is, the removal of material through impacts by high-speed near-Sun meteoroids.