A portrait throughout perihelion of the NH2-rich interstellar comet 2I/BorisovOPEN ACCESS
Sophie E. Deam, Michele T. Bannister, Cyrielle Opitom, Matthew M. Knight, Ryan Ridden-Harper, Darryl Z. Seligman, Alan Fitzsimmons, Aurélie Guilbert-Lepoutre, Emmanuel Jehin, Laurent Jorda, Michael Marsset, Youssef Moulane, Philippe Rousselot, Pierre Vernazza, Bin Yang
Submitted to PSJ, Draft version July 8, 2025
“The interstellar comet 2I/Borisov is the first interstellar object where compositional characterisation was possible throughout its entire perihelion passage. We report all 16 epochs of a comprehensive optical observation campaign with ESO VLT’s integral field spectrograph MUSE, spanning 126 days from 2019 November 14 to 2020 March 19. The spatial dust emission of 2I/Borisov was predominantly smooth, with no seasonal effect. A jet-like feature was consistently visible. The gas production morphology of its coma was also smooth and similar for C2, NH2, and CN:: symmetric around the photocentre. The production rates of these species gently declined into and beyond perihelion, until 2I’s outburst and splitting event in early 2020 March. C2, NH2, and CN: production rates all increased, with NH2 being the most significant; the dust emission also slightly reddened. 2I/Borisov is a carbon-depleted, relatively NH2-rich comet when compared to those comets yet measured in the Solar System.”
