NASA's Hubble Space Telescope has captured an incredible image of a distinctive blue "bubble" floating 30,000 light years away in the Carina constellation. Scientists say the bubble, which formed by interstellar winds about 20,000 years ago, is centered around the Wolf-Rayet (WR) star WR 31a.
"The distinctive blue bubble appearing to encircle WR 31a is a Wolf-Rayet nebula -- an interstellar cloud of dust, hydrogen, helium and other gases," the European Space Agency explained in a statement on NASA's website. "Created when speedy stellar winds interact with the outer layers of hydrogen ejected by Wolf-Rayet stars, these nebulae are frequently ring-shaped or spherical."
Wolf-Rayet stars begin their life with a rapid expansion. In their youth, they are some of the biggest and brightest stars in the sky. In fact, Wolf-Rayet stars can be about 20 times as massive, five to 30 times as hot, and tens of thousands to millions of times as bright as the sun of our own solar system. Therefore, the bubble is estimated to be expanding outward at a rate of 136,700 miles per hour.
However, compared to the sun, which has been active for billions of years and is only in the middle of its cosmic life, Wolf-Rayet stars have a relatively short life span. Within their first 100,000 years, the stars lose about half of their mass. This is in a "the blink of an eye" in cosmic terms.
"It will, therefore, eventually end its life as a spectacular supernova, and the stellar material expelled from its explosion will later nourish a new generation of stars and planets," the agency added.
This is not the first time such a cosmic bubble has been spotted by the Hubble Space Telescope and some are even visible to the naked eye. For example, the brightest and most massive known star, RMC 136a1, is a WR body in the Tarantula Nebula, about 163,000 light years from Earth.
NASA also recently announced plans to build a sort of "super Hubble." They expect this this new telescope, which is called the Wide Field Infrared Survey Telescope (WFIRST), will be about 100 times larger than the Hubble Space Telescope. The hope, scientists say, is to unravel the secrets of the universe and learn more about the evolution of the cosmos.
