Humans squabble all the time with their siblings. But did you know, galaxies stretching quintillions of kilometres in the vast universe also do that? If they tell you otherwise, do not believe them because the Hubble Space Telescope has captured three galaxies engaged in a three-way tug-of-war. While humans’ squabbles can have petty reasons such as candies and toys, galaxies squabble for just one reason — gravitation. Galaxies that have enough gravity can pull out stardust — planets, stars, asteroids, everything– from other nearby galaxies. Or, they can at least try until they are overpowered by the pull of their sibling galaxy. If both their pulls are strong enough, they do not hesitate to even collide.
In the image captured by Hubble, which NASA posted on its website on July 30, three galaxies can be seen in a gravitational squabble. While the galaxy on the left can be seen facing the frame, its sibling in the centre is horizontally perpendicular to the image frame and its disc appears as a short thick line. The galaxy on the right is vertically perpendicular in reference to the image frame and has a long visible trail of shiny stardust. All of the three siblings belong to the galactic cluster Arp 195.
The system of the galaxies belongs to a catalogue of peculiar galaxies, known as the Atlas of Peculiar Galaxies. As you may guess, the classification was done on the basis of the peculiar structures they create during their interaction. The catalogue was originally produced in 1966 by Halton Arp, an astronomer at the California Institute of Technology.
The list of peculiar galaxies includes interacting galaxies — galaxies who disturb each other by the power of their gravitational field. They are also called colliding galaxies. The list also includes dwarf galaxies, which do not have enough mass, and as a result lack enough gravitational pullto form a stable and cohesive galactic structure. Other members are radio galaxies that produce radio jets — highspeed beams of ionised matter are produced by the supermassive black holes at the centre of such active galaxies.