Until now, our Galaxy was seen as a typical example of how everything is arranged in any spiral galaxy. But recently astronomers examined a hundred of the Milky Way’s most similar counterparts and found that most of them are still visibly different.

The Milky Way consists of hundreds of billions of stars in a giant “vortex”: galactic arms revolve around the center, where there is a supermassive black hole of four million solar masses with a relatively insignificant diameter of the orbit of Mercury (about 100 million kilometers). ). The disk of the Galaxy covers an area of ​​\u200b\u200babout a hundred thousand light-years or more, and the Solar System is located in the small Arm of Orion, 26 thousand light-years from the center of the Galaxy.

Spiral galaxies make up the vast majority (60-70%) in the universe. In many respects, this is why astronomers are accustomed to believing that the Earth is in an average environment, and that in any other spiral galaxy everything is approximately the same as in ours. The Milky Way was perceived as a “laboratory” for studying what was happening in the universe. It turns out we are in a different place now.

Recently, astrophysicists have been trying to understand how galaxies are affected by the so-called halo in which they are supposed to be located, like pearls in a shell. It is believed that these are so-called spheres of dark matter, which are five times more abundant than usual in the universe, understood by us and recorded in Mendeleev’s table.

According to calculations, it is the unknown, hidden mass that “holds”, that is, preserves the integrity of the structure of almost all galaxies. Without it, these galaxies would fragment into a scattered collection of stars. Apparently, without dark matter, galaxies would never form. At least that’s what most cosmologists think.

To deal with this dark matter “cocoon”, scientists decided to observe the galactic outskirts, where numerous dwarf satellite galaxies gather. There are more than 50 of them in the Milky Way. The largest ones “weigh” billions of Suns and are visible to the naked eye: these are the Large and Small Magellanic Clouds. But there are other galaxies with a total stellar mass (only about a million Suns and about a thousand light-years in diameter), such as the Pegasus I or Cassiopeia III galaxies.

It is noteworthy that when it comes to the satellites of our galaxy, almost all of them are “dead”: they do not give birth to new stars. This process continues only in the Magellanic Clouds, and only because they have accompanied the Milky Way for the last few billion years. There is an opinion that the process of star formation in satellite galaxies stops precisely under the influence of dark matter.

A team of astrophysicists from the United States compared this situation around the Milky Way with what happens on the moons of other galaxies. We selected 101 galaxies similar to ours in mass and structure. There are 378 satellite galaxies in total. The researchers shared their data for publication in three different papers Astrophysical Journal.

First, they discovered that our small satellite galaxies that “show no signs of life” are certainly not the typical case. Most “copies” of the Milky Way star have been successfully created in satellite galaxies with tens of millions of solar masses, that is, even in rather small ones.

Second, the owners of large moons such as the Magellanic Clouds often have a much larger collection of “little siblings” than the Milky Way.

Thirdly, based on the resulting picture, scientists proposed to change the established model of how galaxies are formed and the “fate” of their satellites: it turns out that the action of dark matter in this process is even less clear than before. .