Such was also the case for an object called SN 2009ip. It’s a star in a galaxy about 80 million light-years away. Or, rather, it was a star.
It first drew attention in 2009, when it flared up brightly in an apparent supernova—a star exploding at the end of its life. But it was soon unmasked as a supernova impostor—a nonfatal outburst from a massive star that only looks like a full-blown supernova.
Following two subsequent flare-ups, astronomers have now concluded that SN 2009ip has gone supernova at last. During a 2012 outburst, the star brightened much more than usual, becoming a billion times as luminous as the sun. And spectroscopic observations revealed that gas was racing outward at roughly 8,000 kilometers per second. Speeds that high indicate a cataclysmic explosion triggered by the collapse of the star’s core. The research will appear in the Monthly Notices of the Royal Astronomical Society. [Jon C. Mauerhan et al., The UNPRecedented 2012 Outburst of SN 2009ip: A Luminous Blue Variable Becomes a True Supernova]
Astronomers now have the rare opportunity to study details of a supernova—both before and after.
—John Matson
