Morphological structures in the inner coma of comet C/2017 K2 (PanStarrs)

Federico Manzini (Stazione Astronomica di Sozzago), Paolo Ochner (University of Padova), Virginio Oldani (Stazione Astronomica di Sozzago), Luigi R. Bedin (OAPD-INAF)

A deep observation session of comet C/2017 K2, with limiting magnitude 23.0 about in r and i Sloan bands was performed on September 12, 2020 with the OAPD-INAF Copernico 1.82m telescope (Asiago, Italy - MPC 098) to study the extent of the coma and any morphological details inside it, with a resolution of 1520 km/pixel on the plane of the sky at the distance of the comet (8.3269 AU from Earth).
Following an image processing to enhance the weakest details, two jet-shaped structures were detected, originating from the nucleus and remaining somewhat collimated before diffusing into the sky background. 
A first jet is located approximately in PA 170° and the second, more widespread, in PA 265°. 
Both structures can be observed over about 25 pixels, corresponding to 37,000 km on the plane of the sky at the distance of the comet. 
It is likely that these structures will show a further evolution over time.
The same image visualized in isophotes shows an asymmetrical coma and allows to estimate the length of the tail (in PA 10°) up to 65 pixels from the nucleus in the anti-solar direction, ie. about 100,000 km on the plane of the sky at the distance of the comet, corresponding to a true length of more than 800,000 km.
These observations suggest a strong activity of the nucleus, modulated by a rotation.
In the images at the link below, North is up and East is left.

Figures and extra material are available at:
https://web.oapd.inaf.it/bedin/files/PAPERs_eMATERIALs/ATel/C2017K2/