A supernova, or stellar explosion, some 200 million light-years away has been traced to its progenitor star, one of only a few times the source of a supernova has been identified based on pre- and post-supernova images.

Astrophysicist Avishay Gal-Yam of the Weizmann Institute of Science in Rehovot, Israel, and astronomer Douglas Leonard of San Diego State University used images from the Hubble Space Telescope to single out the star. In 1997 images, there was a bright light source near where the explosion, dubbed SN 2005gl, was detected in 2005.

In a previous paper Gal-Yam, Leonard and their colleagues had cited this evidence as indicative that the luminous, massive star begat the supernova. But without post-event images, it was not clear that the star had disappeared with the explosion or that the suspect light source had not been a cluster of stars to begin with. Thanks to 2007 Hubble images showing a void where the star (and subsequent supernova) had been, the researchers concluded that the solitary star indeed met its end in supernova SN 2005gl. They report their finding today in Nature.

Until very recently the only other supernova matched to its progenitor star with pre- and post-explosion images was SN 1987A in the nearby Large Magellanic Cloud. Just 168,000 light-years away, supernova SN 1987A was visible to the naked eye when it exploded in its namesake year. Then, in a paper published online by Science last week (that was submitted and accepted for publication after Gal-Yam and Leonard's paper), another pair of researchers identified two progenitor stars that disappeared in supernovae in 1993 and 2003.

Visible, x-ray and infrared image of a supernova remnant courtesy of NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University)