The Flame Nebula is an emission nebula located in the constellation Orion, the Hunter.
The nebula lies at an approximate distance of 1,350 light years from Earth and has an apparent magnitude of 2. It has the designation NGC 2024 in the New General Catalogue.
The Flame Nebula occupies an area of 30 arcminutes of apparent sky. It is part of a vast star forming region known as the Orion Molecular Cloud Complex.
The Orion Molecular Cloud Complex also includes the famous Orion Nebula (Messier 42), De Mairan’s Nebula (Messier 43), the Horsehead Nebula, the Lambda Orionis molecular ring, the emission nebula Barnard’s Loop, and the reflection nebula Messier 78.
The Orion Molecular Cloud Complex is hundreds of light years in diameter. Some parts of it, like the Orion Nebula, are visible to the naked eye, while others can be seen in binoculars and small telescopes.
The Flame Nebula is home to a cluster of several hundred very young stars. 86 percent of these stars have circumstellar disks. The youngest members are concentrated near the cluster’s centre, while the older members lie in the outer regions. This was revealed in a study using data from NASA’s Chandra X-ray Observatory, the Spitzer Space Telescope, the United Kingdom Infrared Telescope, and the 2MASS telescope, which showed that the stars at the cluster’s centre were only about 200,000 years old, while those in the outer regions were around 1.5 million years old.
There are several possible explanations for this. Star formation may be continuing to occur in the central regions of the nebula because the clouds of star forming gas are thicker there than in the outskirts. It is also possible that older stars are in the outer regions simply because they have had more time to move away from the centre. Another theory proposes that young stars are forming in massive filaments of gas that fall toward the cluster’s centre.
The Flame Nebula is illuminated by the bright star Alnitak, Zeta Orionis, the easternmost star in Orion’s Belt. Alnitak is a multiple star system consisting of a hot blue supergiant and two fourth magnitude companions. The supergiant has a visual magnitude of 2.0 and, with an absolute magnitude of -6.0, it is the brightest O-class star in the sky. The star system has a combined visual magnitude of 1.77.
The components of the Alnitak system are members of the Orion OB1 association, a group of several dozen hot giant O and B-type stars found within the Orion Molecular Cloud Complex. The association is divided into several subgroups. The members of the Orion OB1a subgroup include stars northwest of Orion’s Belt, which have an estimated age of about 12 million years. The stars of Orion’s Belt – Alnitak, Alnilam and Mintaka – and stars in the vicinity form the Orion OB1b subgroup and have an average age of 8 million years. The Orion OB1c subgroup consists of the stars in Orion’s Sword, located just under the Belt. These stars are between 3 and 6 million years old. The youngest members of the Orion OB1 association form the Orion OB1d subgroup. These include the stars in the Orion Nebula (M42) and De Mairan’s Nebula (M43).
Flame Nebula – NGC 2024
Constellation: Orion
Distance: 1,350 light years (415 parsecs)
Apparent magnitude: +2
Right ascension: 05h 41m 54s
Declination: -01°51’0.0”
Apparent size: 30′ x 30′
Designations: Flame Nebula, NGC 2024, Sharpless 277, W 12, LBN 953, PMN J0541-0154, SNR G206.5-16.4
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