What causes unusual knots of gas and dust in┬аplanetary nebulas? Seen also in the┬аRing Nebula, the┬аDumbbell Nebula┬аand┬аNGC 2392, the knots’ existence was not initially predicted, and their origins are still┬аnot well understood. Pictured┬аhere┬аis a fascinating image of┬аpart┬аof the┬аHelix Nebula┬аby the┬аJames Webb Space Telescope┬аshowing tremendous detail in┬аinfrared light. The cometary knots have masses similar to the┬аEarth┬аbut have sizes typically several times the orbit of Pluto.┬аOne hypothesis┬аfor the fragmentation and evolution of the knots includes existing gas being┬аdriven out┬аby a less dense but highly energetic┬аstellar wind┬аof the central evolving star. The┬аHelix Nebula┬аis one of the closest examples of a┬аplanetary nebula┬аcreated at the end of the┬аlife of a Sun-like star. Given a technical designation of NGC 7293, the┬аHelix Nebula┬аlies about 650┬аlight-years away towards the constellation of Water Carrier (Aquarius).
