The Butterfly Nebula (Minkowski 2-9) is an outstanding example of a highly collimated outflow from an evolved star. The formation of these extreme nebular geometries -i.e. how the (quasi)spherical symmetry that characterizes all the evolution of a solar-like star is broken when its envelope is ejected- is one of the most debated and controversial topics in the study of the late stages of stellar evolution. Minkowski 2-9 gives us clear hints of what it might going on. This hourglass-shaped nebula is extraordinary in several aspects, but its outstanding characteristic is undoubtedly its
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