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The Triangulum Emission Nebula
NGC 604 lies in a spiral arm of Galaxy M33, 2.7 million light-years from Earth. This nebula is a region in which stars are forming.
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For other uses, see Nebula (disambiguation).
A nebula (Latin: "mist"; pl. nebulae or nebulæ, with ligature) is an interstellar cloud of dust, gas and plasma. Originally nebula was a general name for any extended astronomical object, including galaxies beyond the Milky Way (some examples of the older usage survive; for example, the Andromeda Galaxy is sometimes referred to as the Andromeda Nebula).
[edit] Astrophysics of nebulae
These [regions] are the birthplace of stars. They are formed when very diffuse molecular clouds begin to collapse under their own gravity, often due to the influence of a nearby supernova explosion. The cloud collapses and fragments, forming sometimes hundreds of new stars. The newly-formed stars ionize the surrounding gas to produce an emission nebula.
Other nebulae are formed by the death of stars; a star that undergoes the transition to a white dwarf blows off its outer layer to form a planetary nebula. Novae and supernovae can also create nebulae known as nova remnants and supernova remnants respectively.
[edit] See also
- Solar nebula
- Timeline of the interstellar medium and intergalactic medium
- Messier object
- Images of nebulae
