Supercatastrophic Disruption of Asteroids in the Context of Other Low-Perihelion Bodies

Granvik et al. (2016, hereafter G16) reported that dynamical models of the near-Earth asteroid (NEA) population predict more bodies with perihelia near the Sun than can be accounted for by observations, and proposed that low-perihelion NEAs undergo 'supercatastrophic disruption' (SCD) by an unknown process. Here we examine this hypothesis and extend it to include other low-perihelion bodies such as SOHO comets and meter- and millimeter-sized meteoroids. We find that no NEAs with well-known orbits have crossed inside the G16 limit (~0.08 AU or 16 solar radii) in the last 10⁴ years, providing indirect support for their hypothesis. Asteroid (467372) 2004 LG is an exception. Having spent 2500 years within the G16 limit in the near past, it poses a challenge to SCD. We report that ungrouped SOHO comets show an excess of orbits in the ecliptic plane, and appear at rates consistent with their being small (25 m class) asteroids undergoing SCD, rather than true comets. We find that there is an abundance of millimeter-sized meteoroids inside the G16 limit even when cometary contamination is accounted for, but there are no meter-sized fireballs with known orbits that have perihelia inside even 0.3 AU. The SCD process then doesn't produce meter-sized chunks but may produce abundant millimeter-sized particles. We propose that meteoroid impacts, which reach high speeds and number densities in the near-Sun region, could explain the SCD process as well as contributing both to the unusual light curves of and to the destruction of SOHO comets.