A recent study shows that the intense bar of light you see here, joining the arms of this spiral galaxy, may be a sign of stellar death.

In a paper published yesterday in the Monthly Notices of the Royal Astronomical Society, scientists speculated that bars may kill off disk-shaped galaxies. Galaxies are formed as gravity causes huge clouds of space dust to collapse inwards. When enough dust gathers in a dense enough formation, the center ignites and forms a star. More matter means more gravity, which means even more matter will be attracted to the area. Galaxies are not just groups of stars but star factories. They come in many different shapes, including disks - like the Milky Way.

Some discs form circular spirals. Others have a heavy bar connecting the arms. These bars were once thought to be helpful movers of matter. This material pulls on other material, shifting it around and making bars a sort of matter highway in bar galaxies.


A recent study suggests that bars don't encourage star formation, and may even put the brakes on it. The study made note of what type of galaxies had bars. It turned out that bars were twice as likely to be seen in red galaxies as they were in blue galaxies. New stars burn hot, and give off a blue light. Older stars, lumbering towards darkness, are cooler and give off red light. If bars predominantly show up in red galaxies, they might be signs of decay or they might be killing the galaxies off. According to Doctor Karen Masters at the University of Portsmouth, the reason is still mysterious.

It's not yet clear whether the bars are some side effect of an external process that turns spiral galaxies red, or if they alone can cause this transformation. We should get closer to answering that question with more work on the Galaxy Zoo dataset.

Galaxy Zoo, by the way, is a group of volunteers who help provide and process data for large-scale astronomy studies. If you want to be part of science history, check it out at galaxyzoo.org.


Via The Royal Astronomical Society.