Gigantic X-shaped structure throws (infrared) light on galactic history

Two astronomers have produced the first direct images of a gigantic X-shaped distribution of stars in the center of the Milky Way. The collaboration began when Dustin Lang (University of Toronto) tweeted an image he had recently created. From the tweet, Melissa Ness (MPIA) recognized the image's significance for reconstructing the history of our home galaxy. The X-shaped distribution indicates that the bulge of stars surrounding the center of the galactic disk was formed through dynamical interactions of stars, not by the merger of smaller galaxies with our own.