NGC 2174, located in the constellation of Orion, is approximately 6,400 light years distant. This prominent celestial object is known as the Monkey Head Nebula. Located inside the nebula is NGC 2175. It is an open cluster of relatively new stars that formed from the nebula's molecular clouds of gas and dust. Strong stellar winds and radiation from these large, hot, stars have cleared the central part of the nebula pushing the dust and gas outwardly forming a shell like structure. A dense formation located at the 9:30 clock position in the image above is a stellar nursery which has been the object of scientific study. The Hubble Space Telescope imaged this feature in amazing detail. An image obtained from the Hubble Legacy Archive may be viewed here.
The image above was assembled from three narrowband filtered images. These consisted of SII mapped to red, Ha mapped to green, and OIII mapped to blue. The resulting image is a false color image using the standard Hubble pallet of colors. The stars were overlaid with near true color bi-filtered (Ha-OIII-OIII) data.
1http://wise.ssl.berkeley.edu/gallery_NGC2174.html