Much remains unknown about the physical processes that cause planetary nebulae . Like a butterfly , a white dwarf star begins its life by casting off a cocoon that enclosed its former self. The above cocoon, the planetary nebula designated NGC 2440, contains one of the hottest white dwarf stars known . The white dwarf can be seen as the bright dot near the photo's center. The above false color image and was post-processed by Forrest Hamilton.
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