Astronomers have discovered the most luminous supernova ever recorded. At its peak, the stellar explosion, which erupted in a galaxy 4.7 billion light-years from Earth, was 100 billion times as bright as the sun.
Robert Quimby was hunting for supernovas with a tiny telescope, the 18-inch ROTSE-IIIb at McDonald Observatory near Fort Davis, Texas, when he spotted the explosion. Follow-up observations with the same observatory's 10-meter Hobberly-Eberly Telescope hinted that light emitted by doubly ionized oxygen atoms in the supernova was shifted from its normal position in the spectrum to much longer, or redder, wavelengths. This suggestion of high redshift indicated that the supernova, found in 2005 and dubbed SN 2005ap, came from a remote galaxy. It had to be extremely luminous to be seen at such great distances.
"It [was] so luminous that I originally doubted the distance," says Quimby, now at the California Institute of Technology in Pasadena.