Astronomers at the Massachusetts Institute of Technology in the United States have found an unusual cluster of dark matter in the Toucan II galaxy – a dwarf ultrathin galaxy located relatively close to Earth, at a distance of only 163 thousand light years. This is reported in an article published in the journal Nature Astronomy.
Researchers have discovered stars that belong to Toucan II, but are too far from its center. They are influenced by the gravity of the galaxy, the mass of which turned out to be three to five times greater than originally assumed. According to scientists, the discovery indicates that ancient relict galaxies were also more extensive and massive than previously thought, and contain a large amount of dark matter.
Toucan II also contains stars with extremely low metallicity (metallicity characterizes the number of elements heavier than hydrogen), which were formed in the early Universe.
Dark matter is a hypothetical type of mysterious matter believed to account for over 85 percent of the mass of matter in the universe, excluding dark energy. Each galaxy is believed to have a dark matter halo that traps the stars in it. Without dark matter, the gravity of visible matter would not be enough to prevent galaxies from disintegrating.