Coma and tail of Comet 67P/Churyumov-Gerasimenko during the 2021-2022 apparition

Abstract

We present results on the global activity of comet 67P/Churyumov-Gerasimenko (67P), the ROSETTA target, during its first perihelion passage after the mission and after an encounter with planet Jupiter. 67P was observed by broad-band filter imaging at 33 epochs during 2021 May 21 to 2022 June 1. The mean radial flux profiles suggest that 'equilibrium' conditions for the dust flow in the coma existed from around perihelion until about 100 d thereafter. We propose a scenario for the smaller and larger radial exponents, measured before and after the 'equilibrium' phase. Four coma fans with possible source regions at +40°, -10°, -50°, and -70° latitude on the nucleus are identified. The three fans at southern latitudes may be identical with fan sources seen during post-perihelion in 2015-2016. The rotation axis of 67P may not have changed at all or at least not much (<5°) from the orientation measured during the Rosetta mission at the comet. The dust streamers in the coma originated from observed coma fans, containing mostly dust emitted within days to weeks before observation. Two dust streamers, a long- and a short-lasting one, contained heavy dust grains from emission periods hundreds of days before perihelion. Similar emission periods are obtained for the dust seen in the tail region of the comet. Similarities and differences in the dust activity during the recent apparition with that of the Rosetta mission at the comet are found.