HEIDELBERG, Germany, Dec. 7 (UPI) -- The Crab Nebula, the steadiest source of energetic radiation in the universe, astonished European and U.S. astronomers with giant gamma-ray "hiccups," they say.
The astonishment comes because radiation from the supernova remnant at the center of the nebula was long held to be so constant astronomers used it as a standard "candle" with which to measure the energetic radiation of other astronomical sources, ScienceNews.org reported Tuesday.
That was before two spacecraft recently recorded giant gamma-ray bursts from the nebula, the remnants of a stellar explosion 6,500 light-years from Earth that was observed by humans in 1054.
The suspected source of the energetic flares is electrons blasted out from a pulsar, a rapidly rotating, exploded cinder of a star that lies at the very center of the nebula.
But figuring out exactly how the electrons got powered up from their usual predictable, steady level to be the most energetic charged particles ever associated with an astrophysical object has astronomers searching for new models to explain the phenomenon.
Finding the flares "was a shock," Italian astronomer Marco Tavani said in announcing the discovery at an astronomy symposium in Heidelberg, Germany. In fact, he said, when his team first noticed a sudden, short-lived rise in gamma-ray emissions from the Crab in the fall of 2007, they didn't believe it.
It wasn't until the 2010 outburst was recorded that the team was convinced enough to go public with both findings.
"If you say a steady source like the Crab is variable and it's not true, you burn yourself for life," Tavani said.
