Crab Nebula’s Violent Outbursts Shock Astronomers

[n2doc]

By Ron Cowen, Science News December 8, 2010




HEIDELBERG, Germany — Astronomers consider the Crab Nebula one of the steadiest sources of high-energy radiation in the universe. Radiation from the supernova remnant is believed to be so constant that astronomers use it as a standard candle with which to measure the energetic radiation of other astronomical sources.

That’s why researchers are astounded that two spacecraft recently recorded giant gamma-ray hiccups from the Crab, the remnants of a stellar explosion 6,500 light-years from Earth that was observed by humans in 1054. The intensity of the Crab’s gamma-ray radiation suddenly became two to three times stronger for three days beginning Sept. 19, scientists with the Italian Space Agency’s AGILE telescope reported in a Sept. 22 Astronomical Telegram, an e-mail communication. Researchers with Fermi’s Gamma-Ray Space Telescope found an even larger increase over roughly the same time period, they reported in a telegram on the following day. Both teams also announced they had found evidence of previous flares — the AGILE telescope recorded an outburst in the fall of 2007 while the Fermi team spotted one in February 2009.

The suspected source of the energetic flares, along with steadier radiation emanating from the nebula, is blizzards of electrons spat out by the Crab’s pulsar — the rapidly rotating, exploded cinder of a star that lies at the very center of the Crab Nebula. But figuring out exactly how the electrons got revved up to energies of at least 1015 electron volts — the most energetic charged particles ever associated with a distinct astrophysical object — for so short a time has astronomers at the biannual Texas Symposium on Relativistic Astrophysics, held this year in Heidelberg, Germany, scratching their heads and searching for new models.

Finding the flares “was a shock,” said AGILE team member Marco Tavani of the INAF-IASF in Rome and the University of Rome Tor Vergata, who spoke about the findings at the meeting on Dec. 6 and 7. In fact, when his team first noticed a sudden, short-lived rise in gamma-ray emissions from the Crab in the fall of 2007, soon after AGILE was launched, the researchers didn’t believe it. Only when the craft recorded the 2010 outburst was the team 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 at the meeting.

more
http://www.wired.com/wiredscience/2010/12/crab-nebulas-violent-outbursts-shock-astronomers/

[Stinky The Clown]

1. That crab nebula better not do that here.

It could get banned.

[TheMadMonk]

2. That's 10 to the power of 15 electron volts. cut and past removed formatting.

[Orsino]

3. Glenn Beck immediately disclaims responsibility. n/t