Scientists in Britain, the U.S. and Australia have discovered a cluster of new stars at the edge of the fossil galaxy. This discovery may shed light on the nature of dark matter, as well as reveal the phenomenon of “galactic cannibalism.
Tucana II is an ultrathin dwarf galaxy located 163,000 light-years from Earth. It is considered a remnant of the earliest galaxies.
Some of its stars contain virtually no metal. Consequently, they originated shortly after the Big Bang, when the Universe had no heavy elements yet.
A new study shows that Tucana II is larger than scientists thought. A cluster of stars was detected far from its center.
A team of scientists using the Australian National University’s SkyMapper telescope and data from the Gaia mission was able to find and study nine new stars. They are located at a distance of 3500 light years from the center of the galaxy and are even more ancient than the already known luminaries.
Scientists speculated that they originated elsewhere, and Tucana II arose from the collision of two primitive galaxies. As a result, one of them swallowed up the other. Previously, such cataclysms were known only in theory, but now the first convincing evidence of such “galactic cannibalism” has emerged.
The authors of the scientific paper also determined that distant stars are held in place by the gravitational pull of the galaxy itself. To hold them, Tucana II must have a large mass, but it contains very few stars. It can be assumed to include about four times as much dark matter as previously thought.
The study showed that the first galaxies were probably much larger than is commonly thought. Scientists intend to study other objects to get more information.