Student education

Using NASA's Spitzer Space Telescope to study white dwarf stars, astronomers have found the dusty remains of ancient solar systems.

White dwarfs are the dense glowing embers of Sunlike stars. While their atmospheres should consist entirely of hydrogen and helium, they are sometimes contaminated with heavier elements like calcium and magnesium.These metals really shouldn't be there.That means they are external pollutants.

The rocky debris imaged by Spitzer probably represents the innermost planets of a solar system that were ripped apart by the gravitational forces of their host star at the end of its life. Extrapolating our own Sun's life into the white dwarf phase, simulations show that the Earth may not survive, but that Mars and asteroid belt would probably lie outside of the Sun's grasp.

Perhaps the most exciting and important aspect of this research is that the composition of these crushed asteroids can be measured using the heavy elements seen in the white dwarf. In one case 17 heavy elements were found in one star, yielding a composition that closely matches the equivalent of a combined Earth and Moon. The next step will be to search for those ingredients that may suggest that life-bearing planets may once have existed in these systems.