NASA's Spitzer Space Telescope set its infrared eyes upon the dusty
remains of shredded asteroids around several dead stars. This artist's
concept illustrates one such dead star, or "white dwarf," surrounded by
the bits and pieces of a disintegrating asteroid. These observations help
astronomers better understand what rocky planets are made of around other
stars.
Asteroids are leftover scraps of planetary material. They form early on in
a star's history when planets are forming out of collisions between rocky
bodies. When a star like our sun dies, shrinking down to a skeleton of
its former self called a white dwarf, its asteroids get jostled about. If
one of these asteroids gets too close to the white dwarf, the white
dwarf's gravity will chew the asteroid up, leaving a cloud of dust.
Spitzer's infrared detectors can see these dusty clouds and their various
constituents. So far, the telescope has identified silicate minerals in
the clouds polluting eight white dwarfs. Because silicates are common in
our Earth's crust, the results suggest that planets similar to ours might
be common around other stars.