Explanation : Wolf-Rayet stars can blow bubbles. These unusual stars are much hotter and more luminous than our Sun . All extremely massive stars will eventually evolve though a Wolf-Rayet phase. Approximately 200 Wolf-Rayet stars are known in our Milky Way Galaxy . Wolf-Rayet stars generate bubbles because they continually eject their outer atmosphere as a stellar wind. This outgoing wind of particles typically carries away more than the mass of our Earth each year! The wind is caused by atmospheric particles absorbing outgoing starlight , although many details of this process are unknown. The Wolf-Rayet is the brightest star in the above picture and is in the center of the large bubble in the nebula known as NGC 2359 .
Media Credits & Attribution
Credit and Copyright: P. Berlind & P. Challis (CfA), 1.2-m Telescope, Whipple Obs.