Barred Spiral Galaxy
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure made of stars.
Bars are found in up to 65% of spiral galaxies. They affect the motions of stars, dust and gas. It is believed that bars act a bit like a funnel, pulling matter into the bulge from the disk. This leads to stars forming in bursts within the centre.
Astronomers can look at samples of galaxies from different points in time. The further back we go the fewer barred spirals we see. This might suggest that the bars form as the galaxies grow older. It is also thought that this is only a phase in a spiral galaxies life and that the bars will someday fade. This might leave behind a large core at the centre of the galaxy, with a smaller disk. This could be a possible transition from a spiral to an elliptical galaxy.
It is very difficult to see the true shape of our own galaxy, the Milky Way. By measuring the movement of stars in the night sky, astronomers have suggested that we live in a barred spiral galaxy.