Impossibly Big Supernova

Researchers in Canada have recorded a supernova event with a brightness that seems impossible.

Type Ia supernovae occur when the mass of a white dwarf approaches the Chandrasekhar limit of 1.4 solar masses -- usually by the accretion of matter from a nearby star. These explosions usually have the same brightness and, as a result, serve as 'standard candles' for measuring distances in the Universe.

We've found a supernova that is so bright that it ought to have been impossible," University of Toronto astronomer Andy Howell, lead author of the study, told physicsweb.org. "Now we have to take a hard look at our theoretical understanding of Type Ia Supernovae and figure out how this could have happened."

According to Howell, although it should not be possible for a white dwarf's mass to break the Chandrasekhar limit, this event has shown that "nature has found a way". The researchers estimate that such extreme events are rare, happening no more frequently than in 1 out of 500 supernova Ia events. However, the concern is that other supernovae, not as extreme as SNLS-03D3bb, could contaminate a large sample of blasts.

"We'd still get roughly the right measurements, but it might not be as precise as it could be; especially when it comes to determining the nature of the dark energy that is driving the acceleration of the universe," said Howell. "Any knowledge of the extremes in which the 'candles' work and don't work will be essential for the kind of ultra-precise satellite missions that are being planned."

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