Whatever it is, it’s moving fast, with what the researchers called “a unique trajectory and speed.” So fast, it appears it will eventually break free of the gravitational pull of the Milky Way and shoot off into intergalactic space

It’s not just the speed that’s unusual. The data indicates CWISE J1249 contains less iron and other metals than other observed stars and brown dwarfs, which could mean it’s a very old object, dating back to the early days of the Milky Way.