Peter McCullough at the University of Illinois at Urbana-Champaign and Robert Benjamin at the University of Wisconsin at Madison may have witnessed the first example of a trail left by a white dwarf star shooting through interstellar space¿something astronomers predicted in the early 1980s. The Y-shaped filament, which resembles a jet contrail, measures about 2.5 degrees in length. It was first spotted near the Big Dipper in Ursa Major in 1997, and the researchers suspect the trail is approximately 300 light-years from Earth. They reported their finding in the September issue of theAstronomical Journal.
"We believe the gas trail was produced by the radiation from a white dwarf or some other low-luminosity source zipping through the local interstellar medium and leaving behind an ionized wake," McCullough says. "The problem is that we have not yet identified the source." White dwarf stars, though much bigger than planets, appear very faint. Still, McCullough notes that "the filament's large angular size also suggests it is nearby, and therefore we should be able to identify what created it. The culprit could be sitting right under our noses and we don't recognize it."