A pair of interacting galaxies

NGC 3169 and NGC 3166 make up a pair of interacting galaxies located roughly 70 million light years from earth. The difference in appearance of these two galaxies is striking, while NGC 3169 (galaxy on the left) is an unbarred spiral galaxy, NGC 3166 (the galaxy on the right) has no visible spiral arms.

NGC 3169

A spiral galaxy with tightly-wound arms and interesting looking features. One of the spiral arms appears to be asymmetrical due to the interaction with NGC 3166. Additionally, it features a rather big halo in a wide area around the galaxy core, estimated to contain mass in the order of magnitude of 10⁸ solar masses. At the end of the tidal stream contained in the wider halo around the galaxy, a dwarf galaxy was formed by the star systems part of this halo.

Capturing this very faint halo around the galaxy was the main goal of this photo. While I succeeded somewhat, it could definitely have gone better if I had been able to get more Luminance data.

NGC 3166

Classified as a lenticular galaxy (something between an elliptical and a spiral galaxy), this galaxy has no prominent spiral arms. However, it has a low surface brightness bar structure at the core of the galaxy, which can be seen in my photo. The stars in the disk around its nucleus have a rather low metallicity (higher ratio of hydrogen in their make-up) meaning they are probably older than 8 billion years and therefore belong to some an older generation of stars than our own sun.