M 109 – Barred spiral galaxy


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.

Technical details:

Telescope: Celestron Edge HD14 and 0.7x focal reducer
Mount: Paramount MX+
Camera: ZWO ASI 1600 MM
Filters Astrodon LRGB 1.25″
Exposure: 41 x 6 minutes in luminance et 30 x 6 minutes in RGB
Place: Backyard observatory in Sainte-Sophie, Qc
Date: April 2020


The field of this galaxy is located relatively close to a star of magnitude 2.4 (Phecda) and the internal reflections in my optical tube prevent me from centering the galaxy. I have to move my target a bit so that the internal reflections don’t interfere with my photo. I have tried myself several times with the same result.