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Messier 43

Starforming Nebula M43 (NGC 1982), an emission and reflection nebula, with Open Star Cluster, in Orion

De Mairan's Nebula, Companion of the Orion Nebula

Right Ascension 05 : 35.6 (h:m)
Declination -05 : 16 (deg:m)
Distance 1.3 (kly)
Visual Brightness 9.0 (mag)
Apparent Dimension 20x15 (arc min)

Discovered before 1731 by Jean-Jacques Dortous de Mairan.

Messier 43 (M43, NGC 1982) is the companion of the Great Orion Nebula, M42. It is separated from the great nebula by an impressive, turbulent dark lane, and is lying 7 arcmin north of the Trapezium Cluster.

M43 was first reported by de Mairan in 1731 as a "brilliance surrounding a star" which he thought was "very similar to the atmosphere of our Sun, if it were dense enough and extensive enough to be visible in telescopes at a similar distance" (De Mairan 1733). Charles Messier included in his fine drawing of the Orion Nebula, and assigned it an extra catalog number, M43, on March 4, 1769. Moreover, William Herschel took it into his list with the number H III.1, although normally he careful avoided to assign his numbers to Messier Objects. In his 1811 paper, Herschel states to have observed it as early as March 4, 1774, and cataloged it on November 3, 1783. M43 shows up on the first deep photograph of the Orion Nebula, taken on March 14, 1882 by Henry Draper.

The diffuse nebula M43 surrounds the irregular young "nebula variable" NU Orionis (HD 37061, attn: "N" "U" Orionis, not "Nu Orionis", i.e. the variable star 2-letter designation, not the Greek letter). This star was determined to be of visual magnitude 6.5-7.6; its spectral type was once given as B IV, but was determined to be B 0.5 V by Schild and Chaffee (1969). Apparently, M43 is excited to shine by this star, which is quite cool for a central star of an H II region, and accounts for the comparatively low luminosity, or flux, of M43 at all wavelengths.

M43 contains its own, separate small cluster of stars which have formed in this part of the Orion Nebula.

The dark features along its eastern border are well visible in telescopes starting at about 8 inch. The nebula itself is a fine view even in a 4-inch. Alister Ling, in his semi-recent review of observing the Orion nebula with filters, mentions the Comma shape of this nebula (Ling 1995).

Our image was obtained by David Malin with the 3.9-meter Anglo-Australian Telescope. More information on this image is available.

  • Historical Observations and Descriptions of M43
  • Gallery of M43 images
  • More images of M43
  • Amateur images of M43
  • More images of M42 and M43
  • Infrared images of M42 and M43 (2MASS)
  • UKS images of M42, M43 and NGC 1973-5-7, by David Malin
  • More images of M42, M43 and NGC 1973-5-7
  • Amateur images of M42 and M43 - more amateur images

  • Bill Arnett's Orion Nebula M42/43 photo page, info page.

  • SIMBAD Data of M43
  • NED Data of M43
  • Publications on M43 (NASA ADS)
  • Observing Reports for M43 (IAAC Netastrocatalog)
  • NGC Online data for M43


    Hartmut Frommert
    Christine Kronberg

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    Last Modification: November 7, 2007