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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. 

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