Canis Major Overdensity
The Canis Major Overdensity is the possible closest companion of the Milky Way Galaxy. It lies between the Milky Way's spiral arms and is being slowly pulled apart by the host galaxy's gravity. The dwarf galaxy measures 5000 light years across.
Locations
Globular clusters thought to be associated with the Canis Major Dwarf galaxy include NGC 1851, NGC 1904, NGC 2298 and NGC 2808, all of which are likely to be remnants of the galaxy's globular cluster system before its accretion, or swallowing, into the Milky Way. NGC 1261 is another nearby cluster, but its velocity is different enough from that of the others to make its relation to the system unclear. The Canis Major Dwarf Galaxy may also have associated open clusters, including Dol 25 and H18, and possibly AM 2. It is thought that the open clusters may have formed due to the dwarf galaxy's gravity perturbing material in the galactic disk and stimulating star formation.
