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Definition of planetary nebula in English: planetary nebulanoun Astronomy A ring-shaped nebula formed by an expanding shell of gas round an ageing star. Example sentencesExamples - The Boomerang Nebula is a young planetary nebula and the coldest object found in the Universe so far.
- To obtain direct clue of the presence of magnetic fields in planetary nebulae, astronomers decided to focus on the central stars, where the magnetic fields should have survived.
- Until recently, it was thought that shells around planetary nebulae were a rare phenomenon.
- Astronomers call such an object a planetary nebula, because its round shape resembles that of a planet when viewed with a small telescope.
- One way that astronomers classify planetary nebulae is by the number of axes that they contain.
Definition of planetary nebula in US English: planetary nebulanoun Astronomy A ring-shaped nebula formed by an expanding shell of gas around an aging star. Example sentencesExamples - Until recently, it was thought that shells around planetary nebulae were a rare phenomenon.
- The Boomerang Nebula is a young planetary nebula and the coldest object found in the Universe so far.
- To obtain direct clue of the presence of magnetic fields in planetary nebulae, astronomers decided to focus on the central stars, where the magnetic fields should have survived.
- One way that astronomers classify planetary nebulae is by the number of axes that they contain.
- Astronomers call such an object a planetary nebula, because its round shape resembles that of a planet when viewed with a small telescope.
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