Scientists have found an answer to long unanswered question — What happens when two galaxies collide? Researchers say that what happens post-collision depends on the size of galaxies. If one giant galaxy collides with a dwarf galaxy then the collision stops smaller galaxy from forming new stars. While the rate of formation of stars increases in both the galaxies post-collision if they are similar in sizes. The study was based on analysis of 20,000 merging galaxies.
Andromeda, our nearest major galactic neighbor, is moving fast towards our galaxy Milky way at about 4,00,000 kilometers per hour and will collide with our galaxy in future, says Astrophysicist Luke Davies, from The University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR). However, he further added that there are nearly four billion years left in the collision, but investigating such cosmic collisions lets us better understand how galaxies grow and evolve.
Previously scientists thought that when galaxy smash into each other the rate of production of stars increases by a significant amount due to more concentrated gas clouds which gives extra fuel for faster formation of stars. On the contrary, Dr Davis explained that when two galaxies of similar masses collide then they both increases their stellar birth rate. However, when one galaxy is significantly more heavier than other, then the bigger galaxy starts forming stars at a faster rate while the rate of production of stars decreases in smaller galaxy. This is due to the fact that the bigger galaxy gobbles up its companion’s gas leaving it without any fuel to form new stars.
Apart from unravelling the mystery of galaxy collision; the study has also pointed towards collision between Milky Way and Andromeda four billion years later.
Well, scientists believe that both they galaxies will start affecting star production rate as they come closer to each other, eventually merging up to form a new galaxy. In fact, scientists have given a new name to the galaxy that will form after the collision — ‘Milkdromeda’.
Below is the Andromeda–Milky Way collision simulation.
For the study, Dr Davies used Anglo-Australian Telescope in regional New South Wales.
The study appeared in the journal Monthly Notices of the Royal Astronomical Society