Omega nebula(redirected from Diffuse Nebula M17)
Omega nebula(Swan nebula; Horseshoe nebula; M17; NGC 6618) An emission nebula with a conspicuous bar that lies at a distance of 2200 parsecs in the constellation of Sagittarius, very close to its northern boundary with Scutum. The nebula's apparent magnitude is 7. It is an H II region and a double radio source. The M17SW molecular cloud is a site of massive star formation; the interface between the nebula and M17SW is an example of an edge-on photodissociation region.
Omega Nebula[ō′meg·ə ′neb·yə·lə]
A bright H II region in the constellation Sagittarius that is both a bright far-infrared source and a double radio source. Also known as Swan Nebula.