Interacting Galaxies

INTERACTION GALAXIES

Interacting galaxies are among the most spectacular deep-sky objects. The effects of gravitational interference upon the structure of the galaxies can be dramatic. A good example of interacting galaxies is M51 and Ngc5195. Both are spirals, each about one-half the mass of our own Galaxy. M51 appears nearly face-on and badly distorted by the effects of Ngc5195. M51 is one of the most beautiful galaxies that can be easily observed with backyard telescopes. It is in fact a highly disturbed galaxy sometimes classified as irregular.

Computer-generated models simulating the interaction of both galaxies indicate that Ngc5195 has followed a boomerang trajectory that carried it past M51 millions of years ago. Now it can be found on the far side of M51 and it is mooving away. The circular disk of M51 has been squeezed into an elipse by the gravitational pull of Ngc5195. The encounter of these two galaxies stripped millions of stars from their parent systems and left them adrift in intergalatic space.

Anatomy of M51

Some intergalactic encounters like those of the spiral galaxies Ngc4567/Ngc4568 produce only mild disruptions in the structures of the galaxies involved, while others, as the Stephan Quintet (Ngc 7317/20) and Ngc4631/Ngc4627 look profoundly dynamic and perturbed.