LONDON (Reuters) - Astrophysicists said on Wednesday they had found evidence that some black holes are created by the explosion of a giant star, or supernova.
Scientists believe black holes, the powerful gravitational fields that suck in matter like water going down a drain, result when a supernova collapses or by a tremendous thermonuclear explosion of a supernova.
``We have found evidence for a connection between a supernova explosion and black hole formation,'' Rafael Rebolo, of the Institute of Astrophysics in the Canary Islands, said in a telephone interview.
``For the first time we have been able to find proof of the origin of one of the best black hole candidates in the galaxy. This proof is related to the chemical composition that was present at the time of the formation of the black hole.''
Rebolo and his colleagues in Spain and at the University of California in Berkeley used the Keck I telescope in Hawaii to study Nova Scorpii 1994, a black hole and its orbiting companion star. Their findings are published in the latest issue of the science journal Nature.
The scientists detected very large quantities of magnesium, oxygen, silicon and sulfur in the atmosphere of a star that was present at the time the black hole was formed. They found the star had 10 times the normal content of the elements.
``Our study was motivated by the possibility of detecting the output, the products, of the thermonuclear reactions of any supernova that could have originated the black hole,'' said Rebolo.
The large quantity of the elements has not been seen before in other stars and is synthesized only at very high temperatures which suggest a thermonuclear process such as a supernova explosion.
``This is the first time these elements have been observed in a star linked to a black hole. The content is quite anomalous. We argue that these anomalies are related to the fate of the precursor of the black hole. There is no alternative way to explain this,'' said Rebolo.
In a commentary on the research, John Cowan of the University of Oklahoma said the most logical explanation for the higher abundance of the elements in the companion star of Nova Scorpii 1994 is that they resulted from a supernova explosion of the original massive star in the system.
``We now have the first convincing evidence that at least some black holes are created by supernovae,'' he added.
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