Hubble Finds Atmosphere of White Dwarfs Polluted With Planet Debris
Posted on May 10, 2013
Astronomers using NASA's Hubble Space Telescope have announced the discovery of the atmospheres of two white dwarfs (burned-out stars) polluted with planetary debris. The dead stars are located 150 light-years away in the star cluster, Hyades, in the constellation Taurus.
An artist's impression of a white dwarf with polluted rocky debris left behind by the star's surviving planetary system is pictured above. The astronomers say that infalling asteroids pollute the white dwarf's atmosphere with silicon. Silicon is not found in white dwarfs, but it is found in rocky planets. The researchers say the finding implies that the white dwarf's progenitor star had planets composed of Earth-like material. This suggests that rocky planet assembly is common around stars. A large version of the artwork can be found here.
Jay Farihi, lead author of the study from the University of Cambridge, says in a statement, "We have identified chemical evidence for the building blocks of rocky planets. When these stars were born, they built planets, and there's a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system."
Farihi also says, "Normally, white dwarfs are like blank pieces of paper, containing only the light elements hydrogen and helium. Heavy elements like silicon and carbon sink to the core. The one thing the white dwarf pollution technique gives us that we just won't get with any other planet-detection technique is the chemistry of solid planets."
The researchers say the finding also offers insight into what will happen in our own solar system when our sun burns out 5 billion years from now.
The research paper was published in the Monthly Notices of the Royal Astronomical Society.