Messier 43

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]
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 d'Ortous de Mairan some time before 1731,[3] then catalogued by Charles Messier in 1769.[a] 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[b]), the focus of the H II region, 1,300 ± 160 ly (400 ± 50 pc) away.[c] 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.

  1. ^ a b Cite error: The named reference Sulentic1973 was invoked but never defined (see the help page).
  2. ^ "Messier 43". SEDS Messier Catalog. Retrieved 23 July 2024.
  3. ^ a b Cite error: The named reference Adam2018 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Diaz2011 was invoked but never defined (see the help page).


Cite error: There are <ref group=lower-alpha> tags or {{efn}} templates on this page, but the references will not show without a {{reflist|group=lower-alpha}} template or {{notelist}} template (see the help page).