The mainionizing star in this nebula is the quadruple star systemNU 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 about4.5′, 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 to78 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.
^abSulentic, Jack W.; et al. (1973),The revised new catalogue of nonstellar astronomical objects, Tucson: University of Arizona Press,Bibcode:1973rncn.book.....S.
^"Messier 43".SEDS Messier Catalog. Retrieved23 July 2024.
