This image is a 60 minute exposure with an STL-1301E CCD camera thru Kopernik's 20-inch F/8.1 Ritchey Chretien Cassegrain telescope focal reduced to F/5. The field of view is about 20x24 arc minutes, with North at the top.
This star is the brightest member of NGC 2264 and the brightest in the image above. It is an O-type blue super giant star also known as 15 Monocerotis. This is a very young, massive, and hot star that is about 8,500 times brighter than the sun. It is slightly variable, with a range from between 4.2 to 4.6 magnitude.
The image above shows the brightest portion of a large emission nebula that surrounds the very young Open Star Cluster NGC 2264 (aka The Christmas Tree Cluster). Both the cluster and the nebula cover a much larger area than is shown. The cluster is so young that most of its O, A, and B type stars are still in the final stages of formation. The famous "Cone Nebula" lies just outside the bottom of the image. The distance to this vast star forming region is about 1,100 light years.
NGC 2264 is an open cluster of about 40 stars embedded in a diffuse nebula located in the constellation of Monoceros. The nebula belongs to a much larger complex, which is currently an active star forming region. The region of nebulosity to the right of the bright star is the Fox Fur Nebula. The brightest area of nebulosity (lower right) contains both reflection and emission components. The cluster is very bright and can easily be seen with binoculars. With a small telescope the stars resemble the glittering lights on a Christmas tree. William Herschel discovered the cluster in 1784, the nebula in 1785.
Classification: Open Star cluster
with nebulosity; aka The Christmas Tree Cluster.
Classification: O-Type blue supergiant star; irregular variable star. This is a very young, bright, & hot star; A member of Open Cluster NGC 2264.
George Normandin, KAS
March 29th, 2010