Astronomers at the Massachusetts Institute of Technology in the U.S. have found an unusual accumulation of dark matter in the galaxy Tucana II – dwarf ultrathin galaxy, which is relatively close to Earth, a distance of only 163 thousand light years.
The researchers found stars belonging to Tucan II, but excessively distant from its center. They are influenced by the gravity of the galaxy, whose mass was three to five times greater than originally assumed. According to scientists, the discovery indicates that ancient relic galaxies were also more extended and massive than previously thought, and contain large amounts of dark matter.
Tucan II also contains stars with extremely low metallicity (metallicity is the relative concentration of elements heavier than hydrogen or helium) that formed in the early Universe.
Dark matter is a hypothetical type of mysterious matter that is thought to make up more than 85 percent of the mass of matter in the universe, excluding dark energy. Every galaxy is thought to have a halo of dark matter holding the stars in it. Without dark matter, the gravity of visible matter would not be enough to keep galaxies from disintegrating.