I found these concentric rings (better seen in crop)which seems to be an interference phenomenon with the monochromatic light of the aurora in combination with the flat surface of a filter.
I searched Google for 'aurora ring artifact image ' and found the answer in the second hit, at photo.net.
http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00A5d5
The keyword here is the narrow spectral emission of the aurora:
"Darren Cokin, Nov 12, 2004; 08:40 p.m.
--snip--
Thanks to the University of Alaska forecaster, the explanation follows. "These are interference fringes due to the parallel faces of the filter and to the narrow spectral emission at 5577 Angstroms in the aurora. That green, atomic oxygen emission line is the strongest emission in the aurora near our film and eye peak sensitivity, so it shows up first when there is any device in the optical path which sorts out the spectral emissions." So, don't use filters!"

Update: After all, this could be a capture NX phenomenon, see "Capture NX ring artifact".