At least 30% of disk-shaped galaxies, including the Milky Way, have a thick line, or 'bar', of stars, dust and gas across their centre. A new study shows that these bars are more common in older galaxies than younger ones, suggesting that they might cause galaxies to age more quickly.
Karen Masters at the University of Portsmouth, UK, and her colleagues examined data from 13,665 disk galaxies. The galaxies had already been catalogued by the Galaxy Zoo project, which enlists members of the public to comb through telescope data and classify galaxies. The researchers found that as many as half of redder galaxies — which host only older stars — have bars (pictured, top). By contrast, 80–90% of bluer galaxies — in which stars are currently being born in large numbers — do not (bottom).