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Evidence of an extreme cosmic event involving the death of super-giant stars hundreds of times bigger than the Sun has been discovered by an international research team, including astronomers from The University of Western Australia.

So called "gamma ray bursts" or GRBs produce a flash of gamma rays as a star is collapsing in on itself to form a black hole, an object so bizarre that light cannot escape from it.  GRBs are the most luminous and mysterious explosions in the Universe.

The blasts emit surges of gamma rays - the most powerful form of light - as well as X-rays, and produce afterglows that can be observed at optical and radio energies.

NASA's Swift and Fermi space telescope missions and other spacecraft detect an average of about one GRB each day, and most gamma ray bursts last less than a minute.

But this one produced a high-energy emission for an astonishing seven hours, by far the longest GRB ever recorded.

The research team, led by French astronomer Dr Bruce Gendre, in collaboration with Associate Professor David Coward and Dr Eric Howell from UWA's School of Physics, made a detailed study of GRB 111209A, which first erupted on December 9, 2011.  The team's findings appeared in the March 20 edition of The Astrophysical Journal .

"Only now are we seeing a clear picture of just how extreme these extraordinary events can be," Dr Gendre said.

Professor Coward said the research team found that the only way to produce an Ultra-Long GRB was through the collapse of the most massive stars in the Universe.

"The UWA team showed that these ‘monster' explosions are much rarer than ‘normal' GRBs, and require special conditions," he said.

The astronomers discussed their findings at the 2013 Huntsville Gamma-ray Burst Symposium in the US city of Nashville, Tennessee, a meeting part-sponsored by NASA's Swift and Fermi space telescope missions.

Media references

Associate Professor David Coward (UWA School of Physics)  (+61 8)  6488 4563  /  (+61 4) 23 981 240
Michael Sinclair-Jones (UWA Public Affairs)  (+61 8)  6488 3229  /  (+61 4) 00 700 783