Hubble image reveals blue bubble surrounding Wolf-Rayet star

WASHINGTON, Feb. 29 (UPI) -- A new image captured by the Hubble Space Telescope features a rare Wolf-Rayet star.

The star, known as WR 31a, is part of the Carina constellation and lies some 30,000 light-years from Earth. WR 31a appears surrounded by a blue bubble -- an interstellar cloud composed of gas and dust.

The cloud is mostly made up of hydrogen and helium ejected by the Wolf-Rayet star. Stellar winds interacting with the ejected gas combine to form spherical or ring-shaped clouds.

Astronomers believe the bubble was formed some 20,000 years ago and is expanding at a rate of nearly 140,000 miles per hour.

Also pictured, to the lower right, is a stellar companion to WR 31a. Scientists have yet to name or classify the star.

Wolf-Rayet stars begin their life with rapid expansion. In their youth, they are some of the biggest and brightest stars in the sky. They often expand to a mass 20 times that of the sun, but they quickly dissipate, shedding half their mass in their first 100,000 years.

Just a few hundred thousand years after birth, Wolf-Rayet stars say goodnight with a violent supernova explosion.