concussion ring of the Phi Puma supernova.
A Concussion ring was a phenomenon associated with supernovas, like the Phi Puma supernova. By 2165 the concussion ring of that supernova was over 90 light years in diameter, reaching all the way to Bayard's Planet. (TNG: "The Naked Now", "The Last Outpost", "Datalore", "Conspiracy")
This was seen on an Enterprise computer's star chart, originally a drawing by Rick Sternbach and published, years earlier, on page 151 of the reference titled Spaceflight Chronology.