Planet Formation Mystery Solved?

Scientists think they have solved the mystery of how planets form around a star born in a violent supernova explosion, saying they have detected for the first time a swirling disk of debris from which planets can rise.

The discovery is surprising because the dusty disk orbiting the pulsar, or dead star, resembles the cloud of gas and dust from which Earth emerged. Scientists say the latest finding should shed light on how planetary systems form.

"It shows that planet formation is really ubiquitous in the universe. It's a very robust process and can happen in all sorts of unexpected environments," said lead researcher Deepto Chakrabarty, an astrophysicist at the Massachusetts Institute of Technology.

Details appear in Thursday's issue of the journal Nature.

Using NASA's infrared Spitzer Space Telescope, MIT scientists observed bright radiation released by a disk of rubble around a young pulsar 13,000 light years from Earth. The pulsar was once a giant star that collapsed in a supernova explosion about 100,000 years ago.

While researchers didn't directly see planets forming in the disk, they believe the building blocks are present.

In 1992, another team of scientists found planets circling a different pulsar, but they didn't observe a disk and couldn't tell how the planetary system formed.

Chakrabarty said the debris disk most likely formed from metal-rich material that failed to escape the supernova. The disk resembled that seen around sun-like stars, leading researchers to conclude it might spawn a new planetary system.

If planets did exist in the recently discovered debris disk, they wouldn't be habitable because of the violent process that gave rise to the disk, said astronomer Charles Beichman of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"This is more Chernobyl than Malibu," said Beichman, who had no role in the research.

Scientists have long believed that planets like Earth were formed when dust particles surrounding a young star began to clump, smashing and fusing into one another.

By Alicia Chang