Supernova Alert! Astronomers Spot Warning Outburst

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).
The scientists detail their findings in the Feb. 7 issue of the journal Nature.
Credits NASA-ESA , Space.com and amateur astronomers.