Galactic Collision Revives Dead Galaxies

When two galaxies have a galactic collision and travel into each other, a massive amount of energy is released. Scientists have discovered that this is can be so intense that it revives nearby dead and dormant galaxies. However, it was also discovered by the team of scientists at Leiden Observatory that this revival of the previously dead stars may only be temporary. A dead or dormant galaxy is one that no longer is making new stars and is no longer expanding in size; it is thought to have used up all of its energy. Imaginably, Andra Stroe and David Sobral from the Leiden Observatory witnessed a galactic collision that brought a supposedly dead galaxy back to life, they were very excited.

Galactic Collision Floods Area With Energy

Their study showed that when a galactic collision causes the two galaxies to travel into each other, it causes a huge shockwave, and this is what floods the area with energy, causing the dead or dormant galaxies to be infused with power bringing them back to life. The researchers watched a galactic collision through different telescopes: La Palma-based Isaac Newton and William Herschel Telescopes and Hawaii’s Subaru, CFHT and Keck Telescopes.

Cause of Galactic Collisions

According to the scientist’s research, galaxies are similar to cities that, over time travel closer together, such as a major city growing and overtaking outlying communities. When they get close enough together, they crash into each other and one of the galaxies absorbs the other within the galactic collision. The particular galactic collision that they watched recently was called “Sausage” or CIZA J2242.8+5301. It is located over two-billion light years from the Earth in the northern hemisphere close to the Lacerta constellation.

After the galactic collision took place, the scientists say they have observed previously dead and dormant stars coming back to life and new stars being formed. Part of the reason for this is that after the galactic collision occurs, there is also the formation of high-density cold-gas clouds. High-density cold-gas clouds are needed to be able to make new stars. Scientists have always known that galactic collisions happened, but until this new study, no one knew that the two galaxies that collided into each other were impacted this much.

How Does Galactic Collision Make Stars?

When the collision happens, scientists say the resulting shock wave is going about 9-million kilometers an hour, or 6-million miles an hour. The resulting tsunami makes massive turbulence, causeing an avalanche that in turn causes dense, freezing gas clouds to form. This is actually key in making a dead galaxy come back to life and create new stars. However, these new stars are usually short-lived, and explode themselves into supernovae within a million or so years, which is not a long life for typical stars. Essentially, they run out of the gas they were using as fuel for their existence as soon as the galactic collision calms down.

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