Planets around Dead Stars
| NASA's Spitzer Space Telescope has uncovered new evidence that planets might rise up out of a dead star's ashes. The infrared telescope surveyed the scene around a pulsar, the remnant of an exploded star, and found a surrounding disk made up of debris shot out during the star's death throes. The dusty rubble in this disk might ultimately stick together to form planets. This is the first time scientists have detected planet-building materials around a star that died in a fiery blast. "We're amazed that the planet-formation process seems to be so universal," says Deepto Chakrabarty of the Massachusetts Institute of Technology, principal investigator of the new research. "Pulsars emit a tremendous amount of high energy radiation, yet within this harsh environment we have a disk that looks a lot like those around young stars where planets are [being born]." The finding represents the missing piece in a puzzle that arose in 1992, when Aleksander Wolszczan of Pennsylvania State University found three planets circling a pulsar called PSR B1257+12. Those pulsar planets, two the size of Earth, were the first planets of any type ever discovered outside our solar system. Astronomers have since found indirect evidence the pulsar planets were born out of a dusty debris disk, but nobody had directly detected this kind of disk until now. The pulsar observed by Spitzer, named 4U 0142+61, is 13,000 light-years away in the constellation Cassiopeia. It was once a large, bright star with a mass between 10 and 20 times that of our sun. The star probably survived for about 10 million years, until it collapsed under its own weight about 100,000 years ago and blasted apart in a supernova explosion. Some of the debris, or "fallback," from that explosion eventually settled into a disk orbiting the shrunken remains of the star, or pulsar. Spitzer was able to spot the warm glow of the dusty disk with its heat-seeking infrared "eyes." The disk orbits at a distance of about 1 million miles and probably contains about 10 Earth-masses of material. Read more... This was seized 4 u at NASA |
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