1. Emission nebulaAn emission nebula is a cloud of ionized gas emitting light of various colors. The most common source of ionization is high-energy photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them.
Read “Emission nebula” on English Wikipedia
Read “輝線星雲” on Japanese Wikipedia
Read “Emission nebula” on DBpedia
Read “Emission nebula” on English Wikipedia
Read “輝線星雲” on Japanese Wikipedia
Read “Emission nebula” on DBpedia
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