M51 - The Whirlpool Galaxy

The galaxy M51 nicknamed the Whirlwind galaxy is one of the best known in the spring sky.

Of modest dimensions, it is about 40% smaller than our Milky Way, it is however the dominant galaxy of a group of 6 other smaller ones. This one is also relatively close to us on a cosmological scale since it is located only 30 million light years away.

This group is part of a larger galaxy cluster that includes the very well-known M101 whose popularity increased in 2023 following the explosion of a supernova that was observed by many amateur astrophotographers. This vast group is itself part of the Virgo supercluster of which our Milky Way and Andromeda are also part.

Thanks to its proximity, its ease of observation and its ideal face orientation, M51 is very studied by professional astronomers. The models of spiral arm creation, star formation and the dynamics at work up to the center of the galaxy are thus tested and observed. According to some recent theories following studies on M51, gravitational interactions between galaxies would be at the origin of the spiral arms as well as the presence of a supermassive black hole at the center of the galaxy as is the case in M51

In addition, M51 is an excellent subject for studying collisions between galaxies and gravitational interactions between them. Indeed, NGC 5195, located on the left, is in orbit around M51 according to the latest studies. It would seem that there have already been collisions in the past between the two celestial objects. However, although we are talking about collisions, it should be noted that almost nothing actually comes into physical contact due to gravitational effects. The bridges of matter that can be observed between the two stars would therefore be due to these rapprochements and gravitational interactions. The two galaxies should eventually merge in 1 to 2 billion years. The physiognomy of the new galaxy will then be totally different.

The image presented here is the result of 20 hours of integration with 600-second exposures, or 10 minutes. It was made with a color camera without using a filter.

Equipment used:

- Skywatcher 80ed Evostar
- ZWO 533mc pro
- ZWO 120mm mini
- Optical splitter (guiding)
- AM5
- Asiair plus
- EAF
- OAG
- Stacked with PixInsight
- Processed with PixInsight