Also found in: Thesaurus, Medical, Acronyms, Encyclopedia, Wikipedia.
A nebula, often circular or ring shaped, formed by the ejection of the outer layers from a late-stage, low-mass star.
(Celestial Objects) an expanding shell of gas surrounding a dying star, formed from matter ejected from the star's outer layers; the gas is ionized by the remaining hot stellar core, emitting light in the process
[C18: named from its (occasional) resemblance to a planetary disc]
an expanding shell of thin ionized gas that is ejected from and surrounds a hot, dying star.
A nebula consisting of an expanding shell of gas, mostly hydrogen, that surrounds a hot, compact central star. See more at star.
Switch to new thesaurus
|Noun||1.||planetary nebula - a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star|
nebula - an immense cloud of gas (mainly hydrogen) and dust in interstellar space