Two galaxies are brought together by forces that they cannot see, but that they can feel. It is a mutual gravitational attraction. It’s inevitable: centimeter by centimeter, light-year by light-year, as the cosmic clock ticks through the eons, the galaxies get closer together.
They can’t help it; its movement was caused by small instabilities billions of years ago. And, as they get closer, the galaxies begin to embrace each other of gas and stars that stretch through the tenuous medium that separates them. Then they collide.
These two massive structures are home to hundreds of billions of stars. During the merger, cosmic fireworks collide, mix, and appear.
And what is left after? A dark, dying, broken galaxy – one that will never shine as brightly or as brightly as it could in the days before the great disaster.
The history
This fantastic physical process takes hundreds of millions of years, so considering that we have been observing it for a few decades, it is still not enough to see the development of the drama in real time.
The simulations finally unraveled the mystery of the strangest galaxies – they merge, collide, and mingle.
The force of gravity is sufficient to distort the shapes of the galaxies when an encounter occurs. But the galaxies themselves are mostly empty space. Stars are just tiny dots compared to the huge volumes of space within a galaxy. When you think of these beasts colliding, the closest thing would not be a car accident, but something like two swarms of bees mingling.
Despite this, galaxies contain countless tons of gas and dust that are floating around, harmlessly, living uncomplicatedly as nebulae.
Those nebulae can persist for centuries, but if given a good boost, for example from a nearby supernova shock wave or, in a more relevant example, complex gravitational interactions like two galaxies, they can begin to collapse in on themselves. . fragmenting and condensing to form a new batch of stars.
When two galaxies merge, the rate of star formation increases up to 10 times its normal speed. In a cosmic flash, billions of new stars are born. For a brief moment, astronomically speaking, the merged galaxy will be brighter than ever.
But all that glare comes at a cost, as the chaos of the collision forces you to consume your precious supplies too quickly. Billions of new stars are born, yes, but most will die shortly after the merger.
Irregular galaxies, filled with dark red stars, are the remains of these great cosmic collisions. It is the price they have to pay for a moment of intergalactic glory.
The future of our galaxy
Our Milky Way and the Andromeda galaxy, two giant galaxies in our local part of the universe, are heading toward a huge collision with each other in just a few billion years. Who will dominate in this intergalactic fight?
Like the Cold War doctrine of Mutually Assured Destruction, there will be no winner in this cosmic clash , but at least the Milky Way will be on equal footing with its cosmic rival.
Image credit: NASA, ESA, SAO, CXC, JPL-Caltech, and STScI
