Most spiral galaxies, like our own Milky Way, tend to be symmetrical. However, sometimes a dramatic event can happen to a galaxy and pull it into an asymmetric shape, like what is happening to the galaxy NGC 2276 in the constellation of Cepheus. This galaxy was recently imaged by the Hubble Space Telescope, and though it might look like a typical spiral galaxy if you look at it quickly, on closer inspection you can see that it has an unusually wonky shape.
There are in fact two oddities about this particular galaxy, which are caused by two different types of interaction. In the top right of the image, you can see that one of the spiral arms seems to be peeling away from the main body of the galaxy. This is due to a nearby companion galaxy, NCG 2300. This companion galaxy is exerting a gravitational pull on NCG 2276 and has twisted it out of shape. In fact, it has twisted the galaxy so much that it appears to be face-on to us on Earth, but in fact, the galaxy faces away at an angle.
The other oddity is on the left-hand side of the image. You can see that there are many more blue areas in this region than in the rest of the galaxy. These blue regions are areas of star formation, where new, young stars grow brightly. This star formation is particularly intense in this area due to the galaxy’s interaction with the hot gas which lies between galaxy clusters, called the intracluster medium.
Although we usually think of the space between galaxies as being empty nothingness, in fact, there can be gases such as hydrogen and helium there and even heavier elements such as iron. When it comes close to a galaxy like NCG 2276, this matter can become clumped together under the force of gravity, where it provides material for new stars.
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