Galaxies are not as peaceful and calm as we may think. They not only create stars and survive supernova explosions, but also feel free to resort to cannibalism. The Milky Way is no exception. How many galaxies were on his desk?
You may have already heard that the Milky Way is preparing to face the Andromeda Galaxy (M31). Galactic collision is a standard process in the Universe. But it is worth distinguishing two varieties.
In the first variant large galaxies collide. Here comes the future event between the Milky Way and the Andromeda Galaxy. This is a merger of two large spiral galaxies, which should create a large elliptical monster. The merger will begin in 4 billion years.
Andromeda Galaxy in the night sky after 2 billion years
But there is a second option - when a large galaxy absorbs smaller ones. Usually these are dwarf satellite galaxies that rotate around a large and gradually (against their will) give it stars. This process is also called galactic cannibalism, and the Milky Way has a rather dark story.
One recent study indicates that the Milky Way began to absorb galaxies at the beginning of its life. Scientists have carefully studied more than 60 massive globular clusters and examined the oldest and youngest stars. Analysis of the age and metallicity of clusters allows us to understand where they came from. The findings suggest that the Milky Way was formed due to the absorption at the early stage of metal-rich galaxies. Moreover, the most active nutrition began 12 billion years ago. A little later, the galaxy ate three more galaxies. How much is all?
Here is the M54, captured by the Hubble Camera. This could be another globular cluster, but noted by the fact that it is located in a foreign galaxy. In 1778 he was found by Charles Messier. Located in a dwarf elliptical galaxy in Sagittarius. Only in 1994 did the true nature of his position become clear. The dwarf galaxy is 90000 light-years distant. Ironically, but the cluster does not live long on foreign territory. The fact is that the dwarf galaxy is moving towards us and once they merge.
Scientists believe that the number of absorbed galaxies can reach up to 11-15 pieces. But this is not the end. Right now, the Milky Way stubbornly selects stars from the dwarf elliptical galaxy in Sagittarius, 7000 light years away from us. It is believed that its stars pass into the sleeves of the Milky Way.
It is important to understand that absorption and merging is not a quick and one-time process. The dwarf galaxy in Sagittarius and the Milky Way passed through each other several times. The last time it happened 100-200 million years ago and still continues. Galactic cannibalism is not surprising, because it is a natural development process where a large galaxy absorbs a smaller one.