LBN 990,CDK24,f4.37

LBN 990, Reflection and Emission Nebula in Monoceres 

This region is not very often imaged by amateur astrophotographers as it is near a more well known target NGC 2170, the Angel Nebula. It is 2700 light years distant in the constellation Monoceres  which is located near the celestial equator.  The image is quite striking and has an other worldly appearance. Because of the round shape and red color I think of it as  Mars surrounded by clouds. This image is done in true color where the red is due to hydrogen gas emission and the blue is due to reflected star light.

The star at the very center of this picture is HD 42050, which is a BII blue giant. It is at the center of a  hydrogen gas region known as an HII region and is  responsible for the ionization of  this region producing the red emission. The blue nebula  around and in front of HD 42050 is VdB 70 and is a reflection nebula. Strangely there is not a known catalog entry for the red nebula. The HII region is almost spherical with sharp edge in the upper side. The sharp edge is because HD 42050’s ionizing photons reach their limit at a certain distance and cannot ionizing hydrogen any further.

The region in the upper half of the image is much more gas-rich and it forms an emission region excited by the bright star HD 42050. It actually is the region identified as LBN 990. The LGN is a catalog known as Lynds Bright Nebula. In the lower half, the gas density is lower and consists largely of a reflection nebula which shows up as blue in the image.The image was taken with a Planewave 24 ” telescope in Rio Hurtado Chile by Martin Pugh and processed by Michael Adler.