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By Mike Wall,

An ongoing act of cosmic cannibalism may be responsible for the strange appearance and unprecedented behavior of a gigantic star nicknamed "Nasty 1," a new study reports.

Observations by NASA's Hubble Space Telescope have revealed a disk of gas nearly 3 trillion miles (4.8 trillion kilometers) wide surrounding Nasty 1, which is a massive, rapidly aging object known as a Wolf-Rayet star.

Wolf-Rayet stars start out big, initially containing at least 20 times more mass than the sun. But their hydrogen-dominated outer layers soon puff up and are lost, exposing the objects' helium-burning cores to space. Astronomers aren't exactly sure how this process unfolds, but they have a few ideas. [Top 10 Strangest Things in Space]

An artist's conception depicts an immense disk of gas surrounding a massive, bright Wolf-Rayet star (at center).NASA, ESA, and G. Bacon (STScl)

For example, some scientists think these massive stars' powerful stellar winds blow away their own hydrogen envelopes. Another idea holds that the outer layers are siphoned off by a cannibalistic companion star.

"That's what we think is happening in Nasty 1," study lead author Jon Mauerhan, of the University of California, Berkeley, said in a statement, referring to the second hypothesis. "We think there is a Wolf-Rayet star buried inside the nebula, and we think the nebula is being created by this mass-transfer process. So this type of sloppy stellar cannibalism actually makes Nasty 1 a rather fitting nickname."

Such a disc had never before been seen surrounding a Wolf-Rayet star, researchers said. The nebula is likely only a few thousand years old and lies about 3,000 light-years from Earth, they added.

Several other factors further bolster the cannibalism idea over the stellar-wind hypothesis, study team members said. For one thing, at least 70 percent of all massive stars belong to binary systems. And modeling work suggests that such a star's own winds may not be strong enough to push it to Wolf-Rayet status.

"We're finding that it is hard to form all the Wolf-Rayet stars we observe by the traditional wind mechanism, because mass loss isn't as strong as we used to think," co-author Nathan Smith, of the University of Arizona, said in the same statement.

"Mass exchange in binary systems seems to be vital to account for Wolf-Rayet stars and the supernovae they make, and catching binary stars in this short-lived phase will help us understand this process," Smith added.

The new study was published online Thursday (May 21) in the Monthly Notices of the Royal Astronomical Society.

This is a condensed version of a report from Read the full report. Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+.

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