Planet-Forming Disk Spotted Around Dead Star

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The researchers combined their data with observations from ground-based telescopes and concluded that the disk orbits the pulsar at a distance of about a million miles (1.6 million kilometers) and contains roughly the same mass as ten Earths.

Alexander Wolszczan is a professor of astronomy and astrophysics at Pennsylvania State University in University Park.

Wolszczan was not part of the discovery team but took part in the teleconference. He says that the debris disk almost certainly formed after the supernova explosion, as no pre-explosion disk could have survived a supernova.

The finding fits in with his 1992 discovery of three planets orbiting a pulsar called PSR B1257+12, the first planets of any type ever found outside our solar system.

Wolszczan says the new finding helps confirm a scientific theory on planet formation.

"Now we can more confidently say that planets around pulsars … are probably not that uncommon at all," he said in the teleconference.

Uninhabitable Planets

These pulsar planets are unlikely to harbor life, according to Charles Beichman, an astronomer at NASA's Jet Propulsion Laboratory (JPL), based at the California Institute of Technology in Pasadena.

"We are really looking at an environment that is very hostile," he said in the teleconference.

"This is not beachfront property, this is not Malibu. It's not what the search for habitable planets is likely to find as a very attractive place."

Beichman explains that, for planets to potentially harbor life, they need to be warm enough to support liquid water.

Such planets then need to have the elements of known life—particularly light elements such as hydrogen, oxygen, and carbon—and a source of energy.

"The environment of pulsar planets would be anything but habitable," he said.

While the planets could be close enough to the pulsar to have a warm temperature at the surface, lighter elements are likely to have been thrown off into deep space by the supernova explosion.

Also, the star would have burned up any available hydrogen before it died.

"The fallback material is likely to be very rich in basic elements—iron and things much heavier than what we are used to seeing in large abundance in the solar system," he said.

Nevertheless, he added, today's announcement improves overall understanding of the processes that lead to planet formation.

What's more, Beichman said, "If planets can form around a pulsar, they can form just about anywhere."

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