BERKELEY, Calif., May 22 (UPI) -- The Hubble Space Telescope recently spotted a star never-before-seen in the Milky Way, or anywhere else. The massive star, which lies some 3,000 light-years from Earth, has been tentatively labeled a Wolf-Rayet.
But while most Wolf-Rayet stars are marked by their twin polar lobes of burning gas, the newly discovered star is surrounded by a large, flat disk of gas, measuring some 2 trillion miles wide. Scientists believe they're observing a Wolf-Rayet in a never-before-seen (and likely short-lived) transition phase.
The star's catalog name (NaSt1) inspired astronomers to nickname it Nasty 1. But its strange appearance and the source of its unusual nature align with the moniker.
Wolf-Rayet stars are defined by their large size and exposed insides. As these massive stars are stripped of their hydrogen-filled outer layers, they swell in size, and their super-hot helium-burning cores are revealed.
Until recently, the main explanation for Wolf-Rayet hydrogen depletion was erosion. Scientists believe strong stellar winds from companion stars blow the outer layers of gas away. But this model can't account for all scenarios, and Nasty 1 suggests theft is likely also involved. Astronomers dub the theft "mass-exchange."
"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," Nathan Smith, an astronomer at the University of Arizona in Tucson and co-author of a new paper on the star, explained in a press release.
But thievery isn't a clean business. Often times, gas is lost in the gravitational tug-of-war between the two stars, which may explain the giant gas disk surrounding Nasty 1.
"That's what we think is happening in Nasty 1," said study leader Jon Mauerhan, a researcher at the University of California, Berkeley. "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."
The new study is published in the Monthly Notices of the Royal Astronomical Society.