A team of researchers analyzing data collected by the Sloan Digital Sky Survey over a four-year period discovered tens of thousands of stars at the galaxy's outer edge toward the constellation Monoceros (the Unicorn). At more than 40,000 light years away from the earth the grouping lies on the same plane as the Milky Way and comprises part of a hoop that is nearly 120,000 light years in diameter, the scientists say. "These stars may be what's left of a collision between our galaxy and a smaller, dwarf galaxy that occurred billions of years ago," explains co-lead investigator Heidi Newberg of Rensselaer Polytechnic Institute. "It's an indication that at least part of our galaxy was formed by many smaller or dwarf galaxies mixing together." Results from a second collaboration lend further support to the ring theory. Astronomers using the Isaac Newton Telescopes in the Canary Islands to investigate a different section of the sky found a second set of stars located at a similar distance from the earth.
The Milky Way contains billions of stars, but it is a relatively small band of celestial bodies just outside our galaxy that has caught the attention of astronomers. New research suggests that a previously unseen belt of stars, rotating at 100 kilometers a second, girds the Milky Way. Scientists presented evidence for the ring on Monday at the annual meeting of the American Astronomical Society in Seattle, Wash.