After observing a star at the very center of our Milky Way galaxy for 8 years, Japanese scientists concluded that it came to us from another galaxy. This is the first evidential observation of such an object. Now scientists need to find more details about the mysterious star and its system.

The S-type star, called S0-6, was discovered near Sagittarius A*, the supermassive black hole at the center of our galaxy. S-type stars generally move in very long, long-period orbits. Star S0-6 was no exception, but it orbited a black hole just 40,000 light-years away. Long-term observations of the star confirmed its orbit around the black hole. Since the region where black holes are located is not prone to star formation, it is suggested that this star came there from somewhere else. But from where?

Spectral analysis of starlight helped answer this question. First, a conclusion can be made about the age of the star based on the presence of heavy element lines in the spectrum and their intensity. The less heavy elements it contains, the older it is. Astronomers have estimated the age of S0-6 at 10 billion years. It is only 3 billion years younger than the Milky Way. Second, spectral analysis reveals the chemical composition of the object. It turns out that the chemistry of S0-6 is completely different from that of other stars in the studied region of space. This means that the star was born somewhere else and was only captured by the black hole at the center of our galaxy after a long time.

The chemical composition of S0-6 turned out to be similar to the composition of stars in dwarf galaxies surrounding the Milky Way. Therefore, scientists believe that it comes from an alien galaxy, which should not surprise us. During its lifetime, the Milky Way has swallowed multiple dwarf galaxies, and a star from one of these could well move towards the center and get trapped there by a supermassive black hole.