B A R R E D   S P I R A L S

The Milky Way is a barred spiral galaxy like the six objects pictured on this page (see Spiral Structure of the Milky Way). Like many nearby galaxies, ours may have a somewhat irregular, disrupted appearance, given its long history of violent interactions with smaller nearby galaxies such as the Large and Small Magellanic Clouds.

Large surveys of spiral galaxies similar in age to the Milky Way have shown that more than half (65%) contain central bars. A study by Kartik Sheth and colleagues recently demonstrated that bars are an indication of advanced evolution. They require billions of years to grow out of more compact galactic cores. When the universe was half its present age, less than half of all spiral galaxies were barred.

All text is copyright Raymond Harris 2006-2008. Image credits appear in the accompanying caption.