In a major breakthrough, scientists have solved a space mystery by discovering the origin of metals that contaminated collapsed stars.An international team of astronomers studied white dwarfs, the super-dense remains of sun-like stars that ran out of fuel and collapsed to about the size of the earth.Many of the stars show signs of contamination by rocky material - the left overs from a planetary system, the study showed.While scientists knew that many hot white dwarfs atmospheres, essentially of pure hydrogen or pure helium, were contaminated by elements like carbon, silicon and iron, the origins of these metals were not known."The precise origin of the metals has remained a mystery and extreme differences in their abundance between stars could not be explained," said professor Martin Barstow from University of Leicester.
"We found that in stars with polluted atmospheres the ratio of silicon to carbon matched that seen in rocky material, much higher than found in stars or interstellar gas,” Barstow added.The researchers surveyed 89 white dwarfs, using the Far Ultraviolet Spectroscopic Explorer to obtain their spectra (dispersing the light by colour) in which the "fingerprints" of carbon, silicon, phosphorous and sulphur can be seen, when these elements are present in the atmosphere."The new work indicates that at around a one-third of all hot white dwarfs are contaminated in this way, with the debris most likely in the form of rocky minor planet analogues,” Barstow commented.“It is exciting to realise that they are swallowing up the left overs from planetary systems, perhaps like our own,” he cautioned, implying the ominous fate that awaits earth.The study appeared in Monthly Notices of the Royal Astronomical Society.