M 109 – Barred spiral galaxy

Description:

M 109 is a fine example of a barred spiral galaxy, ie whose spiral arms are not attached to the nucleus but rather to a more or less long bar which includes the nucleus. The most plausible theory concerning this structure describes that these bars result from a  density concentration at the beginning of the evolution of the galaxy. This structure drains the gas flow and thus feeds star nurseries. The bars grow longer as they evolve and eventually disappear.

M 109 is 50% larger than our Milky Way and is located in the constellation Ursa Major, 82 million light years away from us. The other “satellite galaxies” that we see in this photo are at the same distance but we can clearly see the difference in size.