10 July 2013
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Fig. 1
NASA recently published a wonderful image (fig. 1), acquired by the Hubble Space Telescope (HST), a large astronomical observatory in orbit around Earth. The image shows a collision between two distant galaxies. Interestingly, one of the two galaxies, seen below image center, resembles the head of a bird, since its shape has been highly distorted due to the gravitational influence of its companion, an elliptical galaxy, consisting mostly of old reddish stars.
When two or more galaxies pass close to each other, they are said to be interacting, as they become influenced by mutual gravitational forces. Interacting galaxies may eventually collide, and merge, forming one single gigantic galaxy.
The interacting galaxy pair shown in fig. 1 is known as Arp 142, since they were cataloged by the American astronomer Halton C. Arp. They are about 325 million light years away from Earth. The image also shows a bluish much nearer galaxy, located at image top. This galaxy is estimated to be some 250 million light years away. Therefore, it is much nearer than the Arp 142 couple.
References
http://hubblesite.org/newscenter/archive/releases/2013/23/image/a/
Further reading
http://hubblesite.org/
Aymen Mohamed Ibrahem
Senior Astronomy Specialist