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 Dortous de Mairan some time before 1731, then catalogued by French astronomer Charles Messier on March 4, 1769. The De Mairan's Nebula is part of the Orion Nebula, being separated from the main nebula by a dense lane of dust known as the northeast dark lane. It is part of the much larger Orion Molecular Cloud Complex.
The main ionizing star in this nebula is HD 37061, which is positioned near the center of the H II region and located 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 times the mass of the Sun and 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.
The H II region is a roundish volume of ionized hydrogen centered on HD 37061. It has a diameter of about, corresponding to a linear size of. The net hydrogen alpha luminosity of this region is ; equivalent to. There is a dark lane crossing in front of the region from north to south, known as the M43 dark lane.Gallery
