April 20, 2009
Spitzer sees asteroids around dead suns
Astronomers using the U.S. space agency's Spitzer Space Telescope say they have discovered at least one in 100 white dwarf stars has orbiting asteroids.
The international team of astronomers say their finding suggests the orbiting asteroids and rocky planets once hosted solar systems similar to our own.White dwarf stars are the compact, hot remnants of stars such as the sun. The new observations suggest such Earth-sized stars are often polluted by a gradual rain of closely orbiting dust that emits infrared radiation.
The researchers said the data suggest at least 1 percent to 3 percent of white dwarf stars are contaminated in such a fashion and that the dust originates from rocky bodies such as asteroids, which are also known as minor planets. In our Solar System, minor planets are the leftover building blocks of the rocky terrestrial planets like the Earth, the scientists said.
The astronomers said the Spitzer results imply asteroids are found in orbit around a large number of white dwarfs, perhaps as many as 5 million in our own galaxy.
The findings were presented Monday at the University of Hertfordshire in Britain during the European Week of Astronomy and Space Science conference.