Orion complex

Part of the Orion complex. It shows the Orion nebula near the centre, with the Belt of Orion, and Barnard's Loop curling around the image

The Orion complex (sometimes called the Orion molecular cloud complex) is a huge star-forming area in the constellation of Orion.^[1]

It is a large group of bright nebulae, dark clouds, and young star clusters. The cloud is between 1,500 and 1,600 light-years away and is hundreds of light-years across. Several parts of the nebula can be seen through binoculars and small telescopes. Some parts (such as the Orion nebula) are visible to the naked eye.

The nebula is important because of its sheer size. It is also one of the most active regions of stellar formation that can be seen in the night sky. In it are protoplanetary discs and many very young stars. The nebula is very bright in the infrared wavelengths due to the heat-intensive processes involved in star formation. The complex contains dark nebulae, emission nebulae, reflection nebulae, and HII regions.

Nebulae in the complex

A picture of Barnard's Loop, a main part of the nebula complex. Also seen in the image are other nebulae, such as M42

The following is a list of notable nebulae in the larger nebula complex:

The Orion nebula, also known as M42
M43, which is part of the Orion Nebula
IC 434, which contains the Horsehead Nebula
The Horsehead nebula
Barnard's Loop
M78, a reflection nebula
NGC 1999
NGC 2175
- NGC 2174
Various Orion molecular clouds
Flame nebula (NGC 2024)

Also the Orion OB1 Association is part of this complex. This is a group of several dozen hot giant stars of spectral types O and B. These are blue and blue-white stars.

Orion Complex Media

A labeled map of the Orion molecular cloud, with the images taken by IRAS and various telescopes that mapped CO in this part of the sky
Young stars in Orion A and Orion B molecular clouds. The clouds were imaged by Herschel and the newborn stars were imaged by ALMA and the VLA.
Position of the Orion Molecular Clouds
Orion from Leh with the molecular clouds visible.
Orion A seen by ESA's Herschel Space Observatory
Orion B seen by ESA's Herschel Space Observatory
The Lambda Orionis ring seen by NASA's Wide-field Infrared Survey Explorer
H-alpha image of Barnard's Loop, which is part of the Orion–Eridanus Superbubble
The Herbig–Haro object HH 24, which is located in Orion B
These four images taken by the NASA/ESA Hubble Space Telescope reveal the chaotic birth of stars in the Orion complex, the nearest major star-forming region to Earth.