Star whose brightness fluctuates, as seen from Earth
For the novel by Robert A. Heinlein and Spider Robinson, see Variable Star.
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Comparison of VLT-SPHERE images of Betelgeuse taken in January 2019 and December 2019, showing the changes in brightness and shape. Betelgeuse is an intrinsically variable star.
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either:[1]
Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks.
Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes eclipses it.
Many, possibly most, stars have at least some variation in luminosity: the energy output of the Sun, for example, varies by about 0.1% over an 11-year solar cycle.[2]
^Alexeev, Boris V. (2017-01-01), Alexeev, Boris V. (ed.), "Chapter 7 - Nonlocal Theory of Variable Stars", Nonlocal Astrophysics, Elsevier, pp. 321–377, doi:10.1016/b978-0-444-64019-2.00007-7, ISBN 978-0-444-64019-2, retrieved 2023-06-06
^Fröhlich, C. (2006). "Solar Irradiance Variability Since 1978". Space Science Reviews. 125 (1–4): 53–65. Bibcode:2006SSRv..125...53F. doi:10.1007/s11214-006-9046-5. S2CID 54697141.
A variablestar is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in...
VariableStar is a 2006 science fiction novel by American author Spider Robinson, based on the surviving seven pages of an eight-page 1955 novel outline...
Look up Variable, variable, or variables in Wiktionary, the free dictionary. Wikiversity has learning resources about VariableVariable may refer to:...
In astronomy, a semiregular variablestar, a type of variablestar, is a giant or supergiant of intermediate and late (cooler) spectral type showing considerable...
In astronomy, cataclysmic variable stars (CVs) are stars which irregularly increase in brightness by a large factor, then drop back down to a quiescent...
binary, with the optical counterpart being a variablestar. Sirius is another binary and the brightest star in the night time sky, with a visual apparent...
A Cepheid variable (/ˈsɛfi.ɪd, ˈsiːfi-/) is a type of variablestar that pulsates radially, varying in both diameter and temperature. It changes in brightness...
of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus star-forming...
The American Association of VariableStar Observers (AAVSO) is an international nonprofit organization. Founded in 1911, the organization focuses on coordinating...
discovered to be variable, for example δ Sct variables named after the star δ Sct. The first luminous blue variable to be identified as a variablestar was P Cygni...
A flare star is a variablestar that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare...
(pl. novae), or U Geminorum variable, is one of several types of cataclysmic variablestar, consisting of a close binary star system in which one of the...
Mira variables /ˈmaɪrə/ (named for the prototype star Mira) are a class of pulsating stars characterized by very red colours, pulsation periods longer...
the size of the star. This category includes Cepheid and Cepheid-like stars, and long-period variables such as Mira. Eruptive variables are stars that...
E. N. (2009-01-01). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+, 2007-2017)". VizieR Online Data Catalog: B/gcvs. Bibcode:2009yCat...
VariableStar Observers. Retrieved 12 March 2014. Watson, Christopher (4 January 2010). "T Crucis". AAVSO Website. American Association of Variable Star...
the north pole star. Polaris, the brightest star in the constellation, is a yellow-white supergiant and the brightest Cepheid variablestar in the night...
Ladder, Springer, (1999) AAVSO VariableStar of the Month. W Virginis: Spring 2003 PDF / HTML OGLE Atlas of VariableStar Light Curves - W Virginis stars...
these "cluster-type" variables were being rapidly identified in the mid-1890s, especially by E. C. Pickering. Probably the first star definitely of RR Lyrae...
dwarfs. T Coronae Borealis, also known as the Blaze Star, is another unusual type of variablestar known as a recurrent nova. Normally of magnitude 10...
symbiotic binaries show brightness changes and are classified as variable stars. The star Z Andromedae is often considered the prototype of the symbiotic...
luminosity making it a candidate luminous blue variable about 1.6 million L☉ (one third as luminous as the binary star system Eta Carinae), hence a radius of...
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