The stormy life of space objects is full of surprises. Asteroids and comets fall on planets, and the planets themselves sometimes collide with each other.
Sometimes alien stars invade planetary systems, and wandering luminaries can fall prey to monstrous black holes lurking in the core of the stellar galactic islands. The galaxies are also in complex motion.
70 years ago, astronomers noticed that almost a tenth of all galaxies resemble strange clumpy clouds. They were called "irregular galaxies" and for a long time could not understand where such an unusual shape comes from, including luminous halos - halos, stellar barriers and star-gas dust tails stretching for hundreds of thousands of light years.
The riddle of "irregular galaxies" was solved by the outstanding Soviet astronomer B. A. Vorontsov-Velyaminov. Boris Alexandrovich guessed that when galaxies approach each other, they experience a strong mutual attraction, which generates twisting and intertwining streams of stars, dust and gas.
For several hundred million years (which is not so much on a cosmic scale), the original appearance of colliding objects changes dramatically. Their regular shape is distorted, parts penetrate into each other, and ultimately galaxies can merge into a single shapeless mass.
At the same time, the relatively calm life of the "island universes", as Professor Vorontsov-Velyaminov called the galaxies, changes dramatically. Violent star formation begins, illuminated by colossal supernova explosions. At the same time, a monstrous amount of energy is released, comparable to the eruption of the most powerful "energy volcanoes of the Universe" - quasars.
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Merging galaxies, which astronomers grimly call stellar cannibalism, is a common cosmic phenomenon. In fact, when galaxies collide, the stars themselves easily "slip" by, since the interstellar distances are very large compared to their size.
However, waves of disturbance run through the "stellar nursery" - dust and gas clouds, pushing the process of star formation. Something very unusual should happen only when galactic nuclei containing giant black holes collide.
Stars are delicious
Our Galaxy, the Milky Way is a real "predator". Right now, it is capturing a dwarf galaxy in the constellation of Sagittarius, just 50,000 light-years from its core.
In a hundred million years, our cannibal will completely swallow its neighbor, whose stars will become the stars of our Galaxy. The next "dish" of the Milky Way will be the Magellanic Clouds. Ten billion years will pass, and our galactic home will be replenished with their substance.
Generally speaking, the Magellanic Clouds have already become victims of stellar cannibalism from our Galaxy. Indeed, their irregular shape is largely due to the influence of the Milky Way, which is pulling closer and closer to itself the remnants of these two small galaxies, which are in the process of gradual disappearance.
Meanwhile, the Magellanic Clouds themselves are actively "fighting" among themselves. So, the Large Magellanic Cloud gradually "drags" the stars of the Small. At the same time, real gas and dust rivers are formed, carrying many young stars.
Because of the accumulation of cosmic gas and dust, it is extremely difficult to see what is happening, all acts of local stellar cannibalism are detected in infrared rays of telescopes with subsequent computer processing.
Takes a bite
It is especially difficult to detect the processes taking place in "galactic dwarfs", like the galaxy in Sagittarius, which is 10,000 times smaller in mass than the Milky Way. Astronomers believe that cannibal galaxies begin their meal with small "pieces" of star clusters of several thousand or even hundreds of stars, and end with the bulk concentrated around the core.
Collision of the Milky Way and the Andromeda Nebula.
It must be said that the rest of the dwarf galaxies from our immediate environment will one day get to the Milky Way for lunch. Thus, by the example of what is happening in the vicinity of our Galaxy, one can be convinced that star-galactic cannibalism, which consists in the merger and absorption of small galaxies by larger ones, is a common episode in the life of the Universe.
Heavyweight meeting
The Milky Way, however, also did not have long left with impunity to devour the surrounding "galactic dwarfs". Three to four billion years will pass, and our Galaxy will meet with a worthy adversary - the Andromeda Nebula.
This spiral galaxy is considered a semblance of the Milky Way, although it is significantly (2.5 times) larger than our star island in size. The Andromeda Nebula lies at a distance of 2.5 million light years, and its mass reaches 300 billion solar masses.
Its "star population" includes at least a trillion luminaries. Astronomers have found that the Andromeda Nebula and the Milky Way are approaching each other at a speed of 100-140 kilometers per hour.
The process of collision and merger of such "galactic heavyweights" should take many millions of years. The first to touch the "halo shelves" of the mysterious dark matter surrounding galaxies, and then their outer gas and dust clouds.
As soon as gas and dust come together into a single whole, their density will increase sharply during rapid interpenetration. This will cause the matter to heat up, which, coupled with the growing pressure, will ignite myriads of new stars. A violent process of star formation will begin, accompanied by flares, explosions and ejections of colossal lengths of dust and gas jet streams.
Superinsula of Milkomed
The new stellar super-island, which is formed as a result of the merger of the Andromeda Nebula and the Milky Way, has already come up with a name - Milkomeda. But despite the fact that the collision will greatly "rejuvenate" the stars, its appearance will most likely be terrible. It is a pity to realize this, but the galaxies will be completely destroyed. Their spiral structure will first be distorted, and then turn into an interweaving of former stellar arms.
Something terrible is about to happen when two galactic cores touch. Perhaps even a quasar (a source of powerful radio and optical radiation) will flare up, shining as brightly as all the stars of the new supergalaxy.
The collision of the galaxies NGC 2207 and IC 2163 has been going on for 40 million years. In the future, they will be fully merged.
Our Milky Way, together with the Andromeda Nebula and the Triangulum Galaxy, make up the so-called Local Group of galaxies, linked by gravitational bonds. In addition to the above three large ones, the Local Group includes more than fifty dwarf and "irregular" galaxies.
Thus, the Andromeda Nebula has at least 19 satellite galaxies, and the Milky Way has at least 14. All large galaxies, together with their satellites and the composition of the Local Group independent of them, ultimately form a kind of supergalaxy.
This process will take hundreds of billions of years. And here in the center of the new "island universe" a real stellar cannibal will wake up - a cyclopean black hole. A few hundred billion years will pass, and this monster, together with the stars, will absorb all the surrounding matter, leaving behind only a bottomless gap in space-time. However, this is a completely different story.
Oleg FAYG