|
|
Research published in the current edition of the journal Nature suggests that it is asteroids, rather than comets, that sparkle with diamonds. Scientists have known for sometime that tiny nanodiamonds, many of which contain less than 1000 atoms of carbon, are present in many meteorites. The composition of Xenon and Nitrogen trapped within the diamonds is very different from that of our Solar System and thus are thought to have been formed in other stars. In the past nanodiamonds were studied in residues leftover from dissolving meteorites, however, now researchers led by Dr John Bradley, from Lawrence Livermore National Laboratory's Institute for Geophysics and Planetary Physics, have found a way of studying individual diamonds in meteorites and cosmic dust. Instead of dissolving a meteorite in acid the scientists took ultra-thin sections of samples from asteroids and comets and wafted them over acids to remove everything except the diamonds and organic materials. The results were surprising. Nanodiamonds were only found in the dust and meteorites from asteroids and not in the dust from comets.
"The lack of nanodiamonds in the comet dust, collected by NASA aircraft in the atmosphere, suggests that these little gems must have formed within our Solar System rather than coming from outside", said Dr Matthew Genge, a meteorite scientist from the Natural History Museum and member of the research team. "Comets formed in the outer Solar System and have never been heated and so if most nanodiamonds formed in other stars and came from outside the Solar System you'd expect comets to contain lots of them. They don't".
Although the Xenon in nanodiamonds does suggest that some are formed in other stars only one in every million contains a Xenon atom. Most nanodiamonds, therefore, probably form within our Solar System. Just how, nevertheless, remains a mystery.
More info: The Journal Nature
|
