Washington, Nov 16: Astrophysicts have come up with a new theory regarding supernova explosions after observing a superbright supernova last year.

The research team came up with the new theory after observing supernova SN 2006gy, which exploded last year in a flash 100 times brighter than typically observed in supernovae.

The standard model for typical supernova behaviour is a single collapse resulting in the death of the star, resulting in a brilliant flash of light.

The new theory by the research team shows that extremely massive supernovae can produce brilliant bursts of light after shedding shells of material that collide with one another in a manner that more easily converts the kinetic energy of the lost material into light.

The mechanism for this behavior occurs in gigantic stars with masses 100 to 130 times greater than our Sun.

When these huge stars reach the end of their lives, their cores are so hot that they produce pairs of electrons and their anti-matter counterparts, called positrons.

The energy lost in making these particles leads to instability in the star and it begins to collapse rapidly. The collapse, in turn, ignites rapid nuclear burning inside the star. The collapse eventually reverts into a powerful thermonuclear explosion that ejects into space material equivalent to tens of solar masses.

But this ejected shell of material produces only a faint burst of light.

After this first shell is ejected, the process of contraction and explosion begins again and another shell of material is ejected. This time, however, the second shell slams into the first, converting the kinetic energy of all the material into light-producing an extraordinarily brilliant flash like the one observed in SN 2006gy.

"If you went back and looked at the observations of SN 2006gy prior to last year, you might see a first supernova that was very faint, " said Alexander Heger of Los Alamos' Theoretical Astrophysics Group. "The recent flash was probably a second pulse that created the very bright supernova event, " he added.

While previous research has suggested instability of electron-positron pairs leading to supernova behavior, the new study is the first time that it has been suggested that such repeated instability in pulses creates very bright supernovae.

With this new model, multiple pulses of varying strengths are possible, giving rise to a wide variety behaviors in massive stars until they die.

The new research has been carried in the current issue of the journal Nature. (ANI)