NGC 3079, a barred spiral galaxy in Ursa Major

NGC 3079, a barred spiral galaxy in Ursa Major

NGC 3079 is a barred spiral galaxy of some 70,000 light-years across, located 56.4 million light-years away in the constellation Ursa Major. It is moving away from us at 1116 kilometers per second, possibly together with a companion, the elleptical galaxy NGC 3073.

The disk of NGC 3079 is composed of spectacular star clusters in winding spiral arms and dark dust lanes. The most prominent feature of this galaxy is, however, a lumpy “bubble” of hot gas rising from a cauldron of glowing matter in the very center. The bubbele is some 3000 light-years wide and rises over 3500 light-years above the disk of the galaxy, and is created by fierce “winds” (high-speed streams of particles) released during a burst of star formation. The ongoing winds from hot stars mixed with small bubbles of very hot gas blown by superwinds from supernova explosions.

Superwinds are thought to play a key role in the evolution of galaxies by regulating the formation of new stars, and by dispersing heavy elements to the outer parts of the galaxy and beyond. Astronomers may be seriously underestimating the mass lost in superwinds and therefore their influence within and around the host galaxy.

Gaseous filaments at the top of the bubble are whirling around in a vortex and are being expelled into space at 6 million kilometers per hour. Interestingly, this gas will not reach escape velocity and will rain back down onto the galaxy’s disk where it may collide with gas clouds, compress them, and form a new generation of stars. The two white dots just above the bubble are probably stars in the galaxy.

Observations of the core’s structure indicate that those processes are still active. The models suggest that this outflow began about a million years ago. They occur about every 10 million years. Eventually, all the hot stars will die, and the bubble’s energy source will fade away.

The image was taken by the Hubble Space Telescope.
Image Credit: NASA, Gerald Cecil (University of North Carolina), Sylvain Veilleux (University of Maryland), Joss Bland-Hawthorn (Anglo- Australian Observatory), and Alex Filippenko (University of California at Berkeley)

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