The circular filament of stars around the Milky Way may actually belong to the galaxy itself. If so, then the size of the galaxy known to us should be increased by 50 percent, raising the question: what caused this arrangement of stars.
Scientists investigated the data of the Sky Sloan Digital project, which was aimed at re-analyzing the brightness and location of distant stars on the edge of the galaxy. They found that the edge of the galactic disk "wrinkled" in the folds of the stars, like corrugated cardboard.
"These stars, located behind the spiral structure of the Milky Way, may be related," said astronomer Heidi Newberg, from Rensselaer Polytechnic Institute in New York. She and her colleagues suspect that the dwarf galaxy may have passed through the disk of the Milky Way, leaving ripples like a stone thrown into a pond.
Evidence that the so-called Ring of the Unicorn, located more than 65,000 light-years from the center of the galaxy, is in fact part of the Milky Way, was surprised by Newberg, who was part of the team that discovered this formation in 2002.
"The inclusion of the Unicorn Ring in the Milky Way map extends the galaxy's range from 100,000 light-years to 150,000 light-years," said astronomer Yang Xu, from the National Astronomical Observatory of China and former researcher at Rensselaer.