Christmas Tree Cluster (NGC 2264) in Monoceros
Christmas Tree Cluster (NGC 2264) is an extremly bright and extremly obvious open cluster in Monoceros in the center of the field. In long exposed images, the cluster ist surrounded by a symphony of nebulosity whose bright and dark folds seems to ripple across space like visible sound waves. Below the cluster, one can find the famous Cone Nebula, while to the upper right, Fox Fur Nebula (Sh2-273) can be spotted.
Below of the center to the right, Hubble’s Variable Nebula (NGC 2261) can be found, also known as Caldwell 46. William Herschel discovered this fan-shaped glow 1783. The nebulous object includes R Monocerotis, a 10th mag star at the southern tip of the fan. Historically the star has varied between magnitude 9.5 and 13.0.
Long exposed Ha data has been combined with color data to create this image.
[description from O’Meara]