"This is called oxidation, and you can see it when metal turns into rust," he said. When iron is oxidized, it shares its electrons with oxygen, forming a chemical bond between them, Young said. "But in these data, I also see other materials, such as silicon, magnesium, carbon and oxygen - material that accreted onto the white dwarfs from bodies that were orbiting them." "If I were to just look at a white dwarf star, I would expect to see hydrogen and helium," Doyle said. Keck Observatory in Hawaii, that space scientists had previously collected for other scientific purposes. The data Doyle analyzed were collected by telescopes, mostly from the W.M. "Observing a white dwarf is like doing an autopsy on the contents of what it has gobbled in its solar system."
The white dwarf's large gravitational pull shreds the asteroid or planet fragment that is orbiting it, and the material falls onto the white dwarf, she said. "By observing these white dwarfs and the elements present in their atmosphere, we are observing the elements that are in the body that orbited the white dwarf," Doyle said. The closest white dwarf star Doyle studied is about 200 light-years from Earth and the farthest is 665 light-years away. Their strong gravitational pull causes heavy elements like carbon, oxygen and nitrogen to sink rapidly into their interiors, where the heavy elements cannot be detected by telescopes. White dwarf stars are dense, burned-out remnants of normal stars. "We used the only method possible - a method we pioneered - to determine the geochemistry of rocks outside of the solar system." "Learning the composition of planets outside our solar system is very difficult," said co-author Hilke Schlichting, UCLA associate professor of astrophysics and planetary science. "We're studying geochemistry in rocks from other stars, which is almost unheard of," Young said. Doyle did so by analyzing the elements in rocks from asteroids or rocky planet fragments that orbited six white dwarf stars. The scientists, led by Alexandra Doyle, a UCLA graduate student of geochemistry and astrochemistry, developed a new method to analyze in detail the geochemistry of planets outside of our solar system. "We have just raised the probability that many rocky planets are like the Earth, and there's a very large number of rocky planets in the universe," said co-author Edward Young, UCLA professor of geochemistry and cosmochemistry.