long-period variable star
- long-period variable star
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any intrinsically variable star whose light fluctuations are fairly regular and require many months or several years to complete one cycle. They are, without exception, red giant and supergiant stars. Those in one fairly distinct group with periods of about 200 days belong generally to the larger class of stars called Population II (older stars found mainly in the galactic core and halo). Another group, that of variables with periods of a year or more, mostly belong to Population I (
Populations I and II) (younger stars found generally in the spiral arms of a galaxy).
A long-period variable may change a hundredfold in visual brightness, but the variation in energy output is much smaller because at the low temperature of such a star most energy is released at infrared wavelengths rather than as light. Long-period variables are sometimes called Mira stars, after Mira Ceti (Omicron Ceti) in the constellation Cetus, the first star recognized to be variable.
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Universalium.
2010.
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Long period variable — A long period variable is a type of variable star in which variations in brightness occur over long timescales of months or years. The term generally refers to Mira type variable stars (slowly pulsating red giants) although there are other types… … Wikipedia
long-period variable — noun : an intrinsic variable star whose light fluctuations are fairly regular and require many months or several years to complete one cycle … Useful english dictionary
Variable star — Star Star (st[aum]r), n. [OE. sterre, AS. steorra; akin to OFries. stera, OS. sterro, D. ster, OHG. sterno, sterro, G. stern, Icel. stjarna, Sw. stjerna, Dan. stierne, Goth. sta[ i]rn[=o], Armor. & Corn. steren, L. stella, Gr. asth r, a stron,… … The Collaborative International Dictionary of English
Variable star — A star is classified as variable if its apparent brightness as seen from Earth changes over time, whether the changes are due to variations in the star s actual luminosity, or to variations in the amount of the star s light that is blocked from… … Wikipedia
Variable Star — For the astronomical object, see Variable star. infobox Book | name = Variable Star title orig = translator = image caption = author = Robert A. Heinlein Spider Robinson cover artist = Stephan Martiniere country = United States language = English … Wikipedia
Semiregular variable star — Semiregular variable stars are giants or supergiants of intermediate and late spectral type showing considerable periodicity in their light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20… … Wikipedia
long-pe|ri|od variable — «LNG PIHR ee uhd, LONG », a variable star whose period from one peak of brightness to the next is over 100 days … Useful english dictionary
star — starless, adj. /stahr/, n., adj., v., starred, starring. n. 1. any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night. 2. Astron. any of the large, self luminous, heavenly bodies, as the sun, Polaris,… … Universalium
Cataclysmic variable star — Cataclysmic variable stars (CV) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent state. They were initially called novae, from the Latin new , since ones with an outburst brightness visible… … Wikipedia
Star — (st[aum]r), n. [OE. sterre, AS. steorra; akin to OFries. stera, OS. sterro, D. ster, OHG. sterno, sterro, G. stern, Icel. stjarna, Sw. stjerna, Dan. stierne, Goth. sta[ i]rn[=o], Armor. & Corn. steren, L. stella, Gr. asth r, a stron, Skr. star;… … The Collaborative International Dictionary of English
