  Although the debate regarding the origin of the cyano (CN) radical in comets
has been ongoing for many decades, it has yielded no definitive answer to date.
CN could previously only be studied remotely, strongly hampering efforts to
constrain its origin because of very limited spatial information. Thanks to the
European Space Agency's Rosetta spacecraft, which orbited comet
67P/Churyumov-Gerasimenko for two years, we can investigate, for the first
time, CN around a comet at high spatial and temporal resolution. On board
Rosetta's orbiter module, the high-resolution double-focusing mass spectrometer
DFMS, part of the ROSINA instrument suite, analyzed the neutral volatiles
(including HCN and the CN radical) in the inner coma of the comet throughout
that whole two-year phase and at variable cometocentric distances. From a
thorough analysis of the full-mission data, the abundance of CN radicals in the
cometary coma has been derived. Data from a close flyby event in February 2015
indicate a distributed origin for the CN radical in comet
67P/Churyumov-Gerasimenko.
