(see description below)
The Gourd Nebula
Sharpless 2_308 is a large, faint ring nebula surrounding a Wolf-Rayet star in the constellation Canis Major. The name "Gourd Nebula" comes from its resemblance to a Florence Glass Flask (or "Round-Bottom Flask") in a chemistry laboratory.
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. 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.
Although the object is roughly circular, there is a strange set of projections toward the upper left (North is toward the left).