... NGC 2264 - Cone Nebula and Christmas Tree Cluster Region . This is an H II region in the constellation of Monoceros (Greek for Unicorn). The cone shape is a dark absorption nebula of cold molecular hydrogen and dust in front of an emission nebula. The peak of the Christmas Tree is the star (SAO 114264) above the Cone's tip. The base of the tree is the bright variable type O7 star 15 Monocerotis (or S Monocerotis). ... Copyright (c) Amateur Telescope Makers of Boston, Inc. ...