Messier 43

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Messier 43
Emission nebula
H II region
Messier 43 HST.jpg
Infrared view of (part of) De Mairan's Nebula (M43) taken by the Wide Field Channel of Hubble’s Advanced Camera for Surveys
Observation data: J2000 epoch
Right ascension 05h 35m 31.8s[1]
Declination−05° 17′ 57″[1]
Distance1600 ly
Apparent magnitude (V)+9.0
Apparent dimensions (V)20′ × 15′[2]
Notable featuresTrapezium cluster
DesignationsDe Mairan's Nebula, M43, NGC 1982[3]
See also: Lists of nebulae

Messier 43 or M43, also known as De Mairan's Nebula and NGC 1982, is a star-forming nebula with a prominent H II region in the equatorial constellation of Orion. It was discovered by the French scientist Jean-Jacques Dortous de Mairan some time before 1731,[2] then catalogued by French astronomer Charles Messier on March 4, 1769. The De Mairan's Nebula is part of the Orion Nebula (Messier 42), being separated from the main nebula by a dense lane of dust known as the northeast dark lane.[4] It is part of the much larger Orion Molecular Cloud Complex.

The main ionizing star in this nebula is HD 37061 (variable star designation NU Ori), which is positioned near the center of the H II region and located 1,300 ± 160 ly (400 ± 50 pc) from the Sun. This is a triple star system with the brighter component being a single-lined spectroscopic binary. The main component is a blue-white hued B-type main-sequence star with a stellar classification of B0.5V or B1V. It has 19±7 times the mass of the Sun and 5.7±0.8 times the Sun's radius. The star is radiating over 26,000 times the Sun's luminosity from its photosphere at an effective temperature of 31,000 K. It is spinning rapidly with a projected rotational velocity of around 200 km/s.[4]

The H II region is a roundish volume of ionized hydrogen centered on HD 37061. It has a diameter of about 4.5, corresponding to a linear size of 2.1 ly (0.65 pc). The net hydrogen alpha luminosity of this region is (3.0±1.1)×1035 erg s−1; equivalent to 78 L. There is a dark lane crossing in front of the region from north to south, known as the M43 dark lane.[4]



  1. ^ a b Sulentic, Jack W.; et al. (1973), The revised new catalogue of nonstellar astronomical objects, Tucson: University of Arizona Press,
  2. ^ a b Adam, Len (2018), Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer, p. 209,, ISBN 978-3319653853.
  3. ^ "M 43". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 25, 2018.
  4. ^ a b c Simón-Díaz, S.; et al. (June 2011), "A detailed study of the H ii region M 43 and its ionizing star", Astronomy & Astrophysics, 530: 13, arXiv:1103.3628, Bibcode:2011A&A...530A..57S, doi:10.1051/0004-6361/201116608, A57.

External links[edit]

Coordinates: Sky map 05h 35.6m 00s, −05° 16′ 00″