Three galaxies on a collision course: a rare event
You regularly see photos of two colliding galaxies on Scientias. Yet, it can be just a bit more extreme.
The space photo of the week shows three galaxies on a collision course. Astronomers call this trio SDSSCGB 10189. The galaxies are less than 50,000 light-years apart. By comparison, the Andromeda Galaxy, the Milky Way’s closest neighbor, is 2.5 million light-years from Earth.
The photo below clearly shows that the galaxies are now strongly attracting each other and are therefore distorted. For example, the spiral galaxy on the right has an elongated spiral arm.
In the future, the three galaxies will merge to form one large galaxy. Astronomers use this photo to learn more about the formation of giant galaxies in our universe, and in particular the so-called BCGs (Brightest cluster galaxy). They are the heaviest galaxies at the heart of clusters of galaxies (or groups of several galaxies).
Are you curious what shape the future galaxy will take? In the 1970s, computer simulations predicted that merging galaxies would lead to the elliptical galaxies. It is now clear that merging galaxies often become spiral galaxies. Unfortunately, we will not see the final result of the SDSSCGB 10189 merger, as it will take several hundred million years.
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