US and Australian astronomers have formed a new theory after detecting what they believe are the remnants of a smaller galaxy that was swallowed up by the Milky way. The Milky Way is a fairly large galaxy, and we believe it was formed by the merging of a number of smaller galaxies, Rosemary Wyse, professor of physics and astronomy at Johns Hopkins University in Baltimore, Maryland, told the American Astronomical Society in San Diego, California. The theory was formed after the group observed intriguing patterns of star motion and composition in the Milky Way that hinted at the presence of a remnant of a smaller galaxy consumed by the Milky Way billions of years ago.
What's not clear is what merged when, and this is very significant in trying to constrain the theories of how galaxies evolve, added Wyse, who studies the old stellar population survey, an attempt to map out structural details of parts of the Milky Way galaxy. Bureau Report