The Orion Molecular Complex

The Orion Molecular Cloud is a vast complex of nebulae, dark clouds and stellar associations that spans literally hundreds of light years. It is nearly ellipsoid in shape and lies below the galactic plane. For the most part the OMC is an area rich in molecules in the interstellar medium, which is a prerequisite for the formation of stars. There are also areas however, that are characterized as H II regions, areas where the heavy radiation from nearby stars split molecules into their atomic components, hence preventing star formation. This is the main reason why the OMC does not take a coherent shape but rather seems to be a patchwork of nebulae and darker regions.

In early technological astronomy these objects were thought to be independent of each other but with ever more advanced methods of surveying (especially in X-ray and infrared) it became evident that the OMC is a coherent entity and in fact one of the most active regions of star formation near Sol. The nebulae within it are merely the ‘hot spots’ where massive young stars illuminate the surrounding medium and thus create the beautiful shapes we see today. The darker regions scattered about are areas of very densely packed interstellar medium where active star formation is taking place. These are the cradles of protostars and in fact they already abound with T Tauri type stars.

The most prominent deep sky objects in the OMC are:

  • Orion Nebula (M 42, M 43)

  • Running Man Nebula (NGC 1973/6/7)

  • Flame Nebula (NGC 2024)

  • Barnard’s Loop

  • Horsehead Nebula (IC 434, Barnard 33)

  • Witch Head Nebula (IC 2118)*

The OMC is not only a place of stellar birth but of stellar death as well. In fact, the whole region is thought to be the result of multiple supernova shockwaves. There are many star systems bearing stellar corpses within them, namely black holes and neutron stars; on several occasions even multiple of these can be found in a single star system.

Prominent stars of the OMC are:

  • Betelgeuse (M-type Red Giant), runaway star ejected from Orion OB1

  • Rigel (B-type Binary)

  • Orion’s Belt: Mintaka, Alnitak, Alnilam (ingame: Epsilon Orionis)

  • Sigma Orionis (O-type)

  • HIP 24709 (B-type Giant, 2 Black Holes)

  • EZ Orionis (G-type Supergiant)

  • Lam01 Orionis (O-type, Black Hole), Lambda Orionis Cluster

  • HD 37397 (Black Hole, stunning views!)

  • HD 38563 North/South/C (2 B-type systems, 1 A-type Supergiant)

The OMC is also part of the Orion-Eridanus Superbubble, an expanding area of superheated gas approximately 1,200 light years across, which was formed by various overlapping supernova remnants from exploding stars of the Orion OB Asscociation.

(*) According to some scientists, the Witch Head Nebula may not be a member of the OMC in itself but rather an illuminated filament on the fringe of the Orion-Eridanus Superbubble. As such, it has been included her nevertheless

The OMC also contains various regions of space that are permit-locked and thus cannot be accessed by current FTL drive technology. These regions are:

  • Horsehead Dark Region Sector

  • Col 70 Sector

As these sectors are very much central to the whole area, navigating around them can be a bit of a pain. Route plotting in advance is recommended.

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