Messier 43
Emission nebula
H II region
Emission nebula Messier 43 in Orion
Observation data: J2000 epoch
Right ascension05h 35m 31.8s[1]
Declination−05° 17′ 57″[1]
Distance1,300 ± 160 ly (400 ± 50 pc) ly
Apparent magnitude (V)9.0[2]
Apparent dimensions (V)20′ × 15′[3]
ConstellationOrion
Notable featuresTrapezium cluster
DesignationsDe Mairan's Nebula, M43, NGC 1982[4]

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 d'Ortous de Mairan some time before 1731,[3] then catalogued by Charles Messier in 1769.[lower-alpha 1] It is physically part of the Orion Nebula (Messier 42), separate from that main nebula by a dense lane of dust known as the northeast dark lane.[5] 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[lower-alpha 2]), the focus of the H II region, 1,300 ± 160 ly (400 ± 50 pc) away.[lower-alpha 3] 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 (M☉) and 5.7±0.8 times the Sun's radius (R☉). It is radiating over 26,000 times the Sun's luminosity (L☉) 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.[5]

The H II region is a roundish volume of ionized hydrogen. It has a diameter of about 4.5′, at its distance meaning it measures 2.1 ly (0.65 pc). The net (meaning omitting the star) 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 the whole west-centre strip from north to south, known as the M43 dark lane, which forming a swirling belt extension to the south links to Orion's northeast dark lane. All of these resemble a mixture of smoke rising from a chimney and in watercolour broad and fine dark brushstrokes, at many wavelengths.

See also

References and footnotes

  1. 1 2 Sulentic, Jack W.; et al. (1973), The revised new catalogue of nonstellar astronomical objects, Tucson: University of Arizona Press, Bibcode:1973rncn.book.....S.
  2. ↑ "Messier 43". SEDS Messier Catalog. Retrieved 29 April 2022.
  3. 1 2 Adam, Len (2018), Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer, p. 209, Bibcode:2018imor.book.....A, ISBN 978-3319653853.
  4. ↑ "M 43". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 25, 2018.
  5. 1 2 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.
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  1. ↑ On March 4
  2. ↑ Full name: NU Orionis
  3. ↑ Gaia Data Release 2 gives a parallax that would place it 1,706 ± 36 light-years (523 ± 11 pc) away
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