Messier 43

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.

Messier 43

Emission nebula
H II region
Emission nebula Messier 43 to the northeast of the well-known M42 Orion Nebula
Observation data: J2000 epoch
Right ascension	05h 35m 31.8s[1]
Declination	−05° 17′ 57″[1]
Distance	1,300 ± 160 ly (400 ± 50 pc) ly
Apparent magnitude (V)	9.0[2]
Apparent dimensions (V)	20′ × 15′[3]
Constellation	Orion
Notable features	Trapezium cluster
Designations	De Mairan's Nebula, M43, NGC 1982[4]
See also: Lists of nebulae

The main ionizing star in this nebula is the quadruple star system NU Orionis (HD 37061), the focus of the H II region, 1,360 ± 30 ly (417.0 ± 9.2 pc) away.^[6]

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.

Gallery

• 
  Hubble Space Telescope view of M43
• 
  Infrared view of (part of) De Mairan's Nebula (M43)
• 
  A proplyd being ionized by HD 37061 (image with JWST).

See also

• List of Messier objects