For 10 points, identify these clouds of gas and dust, named for resembling objects like Uranus.
Butterfly-shaped bipolar examples of these objects in the center of the Milky Way were shown to be aligned with the plane of the galaxy. An object named Calabash is an example of a "proto" stage in the formation of these objects that occurs after ultraviolet light from a core begins to ionize the surroundings. These objects' formation is the end result of the (*) asymptotic giant branch, since they form when a giant of 0.8 to eight solar masses ejects its outermost layers. For 10 points, identify these clouds of gas and dust, named for resembling objects like Uranus.
Butterfly-shaped bipolar examples of these objects in the center of the Milky Way were shown to be aligned with the plane of the galaxy.
planetary nebulae [accept protoplanetary nebulae; prompt on just nebulae or emission nebulae; don't prompt on "molecular clouds" or "protoplanetary disc" since those are different things]