Hubble Space Telescope has observed a hefty, rapidly aging star that is so odd, it has been nicknamed "Nasty 1" (playing off its catalog name NaSt1).The star may represent a brief transitory stage in the evolution of extremely massive stars.
First discovered several decades ago, Nasty 1 was identified as a Wolf-Rayet star, a rapidly evolving star that is much more massive than our sun. The star loses its hydrogen-filled outer layers quickly, exposing its super-hot and extremely bright helium-burning core.
Viewing the Nasty 1 system hasn't been easy. The system is so heavily cloaked in gas and dust, it blocks even Hubble's view of the stars. So Mauerhan's team cannot measure the mass of each star, the distance between them, or the amount of material spilling onto the companion star.
The chaotic mass-transfer activity will end when the Wolf-Rayet star runs out of material. Eventually, the gas in the disk will dissipate, providing a clear view of the binary system.
"What evolutionary path the star will take is uncertain, but it will definitely not be boring," said Mauerhan, according to the press release. "Nasty 1 could evolve into another Eta Carinae-type system. To make that transformation, the mass-gaining companion star could experience a giant eruption because of some instability related to the acquiring of matter from the newly formed Wolf-Rayet. Or, the Wolf-Rayet could explode as a supernova. A stellar merger is another potential outcome, depending on the orbital evolution of the system. The future could be full of all kinds of exotic possibilities depending on whether it blows up or how long the mass transfer occurs, and how long it lives after the mass transfer ceases."
Reference:
"Multiwavelength Observations of NaSt1 (WR 122): Equatorial Mass Loss and X-rays from an Interacting Wolf-Rayet Binary," Jon Mauerhan et al., Monthly Notices of the Royal Astronomical Society, 1 July 2015, Vol. 450, No. 3 [https://mnras.oxfordjournals.org/content/450/3/2551].
