Supernova alert! Astronomers spot warning sign

Astronomers have identified the early warning sign of an imminent supernova: a stellar belch that could indicate the star will explode within a month or two.

By Charles Q. Choi,?Space.com / February 11, 2013

The image shows a simulation of a collision between two shells of matter ejected by a massive star in two subsequent pulsational pair-instability supernova eruptions, only years apart, just before the star dies. Image released Feb. 7, 2013.

Ke-Jung Chen / School of Physics and Astronomy, Univ. Minnesota

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Forecasting when stars will die in giant explosions may one day be possible by looking for the warning outbursts they release beforehand, researchers say.

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Supernovas are the most powerful stellar explosions in the universe, visible all the way to the edge of the cosmos. These stars detonate for two known reasons: either from gorging on too much mass stolen from a companion star or by running out of fuel and abruptly collapsing.

Astronomers have suggested that stars can give off smaller explosions just before they go supernova. To find out more about supernovas, researchers used three telescopes ? the Palomar Observatory, the Very Large Array and NASA's Swift mission ? to investigate a star 500 million light-years away. The star, which had about 50 times the mass of the sun, ultimately detonated as a supernova named SN 2010mc.

The researchers' data suggest that 40 days before the final explosion, the dying star produced a giant outburst, releasing as much matter as 1 percent the mass of the sun ? about 3,330 times the mass of Earth ? at about 4.5 million mph (7.2 million km/h). [Photos of Great Supernova Explosions]

"What is surprising is the short time between the precursor eruption and the eventual supernova explosion; one month is an extremely tiny fraction of the 10-million-year lifespan of a star," said one of the study authors, Mansi Kasliwal at the Carnegie Institution for Science in Pasadena, Calif.

This explosion radiated "about a million times more than the energy output of the sun in an entire year," author Mark Sullivan of the University of Southampton in England told SPACE.com. But this precursor "is still about 5,000 times less than the energy output of the subsequent supernova."

Source: http://rss.csmonitor.com/~r/feeds/science/~3/sab4KOUlSWI/Supernova-alert!-Astronomers-spot-warning-sign

marco scutaro