Astronomers suspect that the bubble is being blown by high-speed streams of particles released during a burst of star formation. Gaseous filaments at the top of the bubble whirl around in a vortex and are expelled into space. Eventually, this gas will rain down upon the galaxy's disk where it may collide with gas clouds, compress them, and form a new generation of stars.

Glowing gas is seen as red and starlight is blue-green. Two white dots just above the bubble are probably stars in the galaxy, said scientists involved in creating the images.

The close-up shows the bubble's surface is lumpy, consisting of four columns of gaseous filaments. Each filament is about 75 light-years wide. Velocity measurements taken by the Canada-France-Hawaii Telescope in Hawaii show that the filaments are ascending at more than 4 million miles an hour (6 million kilometers an hour). As they approach their full height, they spread out into the surrounding space.

The bubble formed when winds coming from hot stars mixed with smaller bubbles of hot gas created by exploding stars called supernova, researchers say. Observations of the core's structure by radio telescopes indicate that those processes are still active. This outflow is thought to have begun about a million years ago.

Eventually, the hot stars will die, and the bubble's energy source will fade away.

Hubble's Wide Field and Planetary Camera 2 snapped this picture in 1998. The results appear in the July 1, 2001 issue of the Astrophysical Journal.

Click here for more news and information about Hubble.