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The Gourd Nebula
Sharpless 308 is a large, faint ring nebula surrounding a Wolf-Rayet star in the constellation Canis Major. The Wolf-Rayet star is the bright, blue star near the center of the image and has been the subject of considerable research. (The large yellow star is Omicron 1 CM.) The nebula has an age of 70,000 years and an expansion velocity of 60 km/s. At an estimated distance of 5,200 light-years, it is one of the closest Wolf-Rayet stars to our solar system. The bubble is large, taking up nearly 3/4 degree, and is the result of fast Wolf-Rayet winds sweeping through slower red supergiant winds. The blue color of the nebula is mapped from the OIII oxygen ion, which dominates the nebula's emission.