Big Particle Emission from Comet 67P/Churyumov-Gerasimenko

Abstract

Big (millimeter-sized) particles released from a comet are displayed in a comet trail rather than in the tail. A comet tail is an extended ephemeral phenomenon that is caused generally by sub-millimeter sized particles that were released during the ongoing apparition of the comet in the inner solar system. A dust trail is defined as a concentration of big (mm-sized) particles close to the orbit of the parent comet. The distribution along the orbit comes from the fact that big particles are emitted from the nucleus at low emission speeds (a few m/s) and that the radiation pressure force only weakly modifies their orbits from the orbit of the parent comet. A dust trail of 67P/Churyumov-Gerasimenko (C-G) — the target comet of the Rosetta mission — has been found in IRAS observations in the infrared and in recent ground based observations at visible wavelength. Simulations of micron- to centimeter-sized particle emissions from C-G have been performed. Our results show that mm-sized particles that were emitted during previous perihelion passages have a distribution along the orbit of the comet and in vertical extent which is compatible with trail observations in spring 2003.