This is the Cone Nebula region (Sh2-273) in Monoceros. It is located 6.5 degrees south of Alhena (Gamma Geminorum) and is 2,700 light-years away.

Sh2-273 is an active star-forming region strewn with gas that glows and dust that reflects light from hot young stars that have been born recently.

NGC 2264 is designated as a star cluster with nebulosity, i.e. the Christmas Tree Cluster and Cone Nebula. The triangular-shaped cluster has its base parallel to the top of the frame including S Monocerotis, the brightest star in the image at top center. The point of the Christmas Tree is the star HD 47887, a 7.17 magnitude star that lies just above the Cone Nebula at the bottom of the frame. The Christmas Tree is seen upside down here. Other stars in the cluster are 8th and 9th magnitude.

The cluster is part of the Monoceros OB1 stellar association, a group of young stars that formed out of the gas and dust 1 to 4 million years ago.

William Herschel discovered the cluster and nebulae in 1784 and 1785 respectively.

The Fox Fur Nebula is an emission nebula that lies to the right of S Monocerotis and just above and to the right of the blue reflection nebula.

S Monocerotis, a blue-white type-O supergiant star, is the brightest star in the image and it is a quadruple star that varies in magnitude from 4.2 to 4.6. It can be seen with the unaided eye, and is also designated as 15 Monocerotis. Its luminosity is 8,500 times that of the Sun. It lies 1,000 light-years away.

This area is powered by ultraviolet light from S Monocerotis and the other hot young blue stars in the Christmas Tree Cluster.

The Cone Nebula, LDN 1613, is a dark nebula seen at the bottom of the image. It is 7 light-years long, and it is located 2,500 light-years away from Earth.

The distinctive shape of the Cone Nebula is caused by gas and dust in a molecular cloud being shaped by energetic stellar winds from hot young stars that have recently formed inside the nebula.

Ultraviolet light from newly formed stars in the Christmas Tree Cluster, just to the north, heats the edges of the dark molecular cloud. Hydrogen gas is released by this heating into the area surrounding the cloud where it glows red from ionization caused by the hot O and B type stars in the cluster. Over time only the most dense portions of the original molecular cloud will be left and these regions may form into stars and planets.

William Herschel discovered the Cone Nebula in 1785.

North is to the top in the above image.

Cone Nebula Area Catalogs: Sh2-273, NGC 2264 Common Name: Cone, Conus Object Type: EN, RN and DN Complex Area Size: 53.54' x 79.92' Constellation: Monoceros Image Field Centered At: RA: 06h 40m 56s Dec: +09° 49' 53"