Exploding stars the third kind.

The remains of a supernova, three hundred years after the explosion of a very massive young stars.

Keywords: calcium, astrophysics, supernova.

A third category of supernova appears to have been identified. It would explain why calcium, an element essential to life, is much more common in the universe that current theories do not predict.

This is an issue of crucial importance that an American team of astrophysicists has perhaps provide an answer. In a paper published Thursday in Nature, researchers have identified a third type of supernova may be very common and releasing large amounts of calcium. That explains why this element is essential to life is much more than expected in the universe.
All elements called complex, such as silicon, iron and calcium are produced both by nuclear reactions in stars and heart at the time of explosion, when all those elements are scattered throughout the universe. So far, two major models of explosion existed. The very massive stars (more than 8 solar masses) may indeed collapse on themselves, in their youth, when the internal nuclear reactions no longer able to compensate the gravity force that pushes them to contract. The heart explodes while projecting the material in all directions. But some small stars, called white dwarfs, can also disintegrate after having lived much longer. This is the second model. When these stars accumulate large amounts of degraded material around them called, is the explosion. Just as if we had put too much air in a balloon.

Experts do not all agree:
Problem by conducting a comprehensive study of more than 100,000 million supernovae, a Dutch team in 2007 had led to this curious result: there would be a half times more calcium in the universe than the forecast based on these two models . Clearly, something was missing. The few cases of observations of supernovae appear to emit large amounts of calcium in previous years offered few avenues for research. It remained to show that they were not anomalies, and although they represented a new type of explosion uncommon.
It is in this context that we read the recent work of Hagai Perets, an astrophysicist at the Harvard-Smithsonian Center of Astrophysics. By looking carefully at the data collected during the observation of these supernovae, he showed his team that it could be the explosion of a white dwarf of a new type, just missed. This would be accumulating helium from a twin star that dwarfs reach a point of explosion part. The whole heart of the star would not be dispersed, but a large amount of calcium would be produced and emitted during the explosion. The large number of such stars would suggest that these supernovae could be common.
So, mystery solved calcium? The track is appealing. But in the same issue of Nature, a Japanese team offers an explanation opposed derived from the observation of a supernova quite similar. Although located in a galaxy where there are only old stars, the researchers estimate probable whether the explosion of a young and big star in a very small nursery located in of the galaxy. There would be no new type of supernovae, and would remain difficult to explain why there is this model as much calcium in the universe. Stay tuned.