Variable stars which exhibit non-radial pulsations
Alpha Cygni variables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the same time other parts expand. They are supergiant stars of spectral types B or A. Variations in brightness on the order of 0.1 magnitudes are associated with the pulsations, which often seem irregular, due to beating of multiple pulsation periods. The pulsations typically have periods of several days to several weeks.
The prototype of these stars, Deneb (α Cygni), exhibits fluctuations in brightness between magnitudes +1.21 and +1.29. Small amplitude rapid variations have been known in many early supergiant stars, but they were not formally grouped into a class until the 4th edition of the General Catalogue of Variable Stars was published in 1985. It used the acronym ACYG for Alpha Cygni variable stars.[1] Many luminous blue variables (LBVs) show Alpha Cygni-type variability during their quiescent (hot) phases, but the LBV classification is generally used in these cases.
A large number (32) were discovered by Christoffel Waelkens and colleagues analysing Hipparcos data in a 1998 study.[2]
^Kholopov, P. N.; Samus', N. N.; Frolov, M. S.; Goranskij, V. P.; Gorynya, N. A.; Kireeva, N. N.; Kukarkina, N. P.; Kurochkin, N. E.; Medvedeva, G. I.; Perova, N. B. (1996). "VizieR Online Data Catalog: General Catalog of Variable Stars, 4th Ed. (GCVS4) (Kholopov+ 1988)". VizieR On-Line Data Catalog: II/139B. Originally Published in: Moscow: Nauka Publishing House (1985–1988). 2139: 0. Bibcode:1996yCat.2139....0K.
^Cite error: The named reference waelkens 1998 was invoked but never defined (see the help page).
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AlphaCygnivariables are variable stars which exhibit non-radial pulsations, meaning that some portions of the stellar surface are contracting at the...
Bayer designation is α Cygni, which is Latinised to AlphaCygni, abbreviated to Alpha Cyg or α Cyg. α Cygni (Latinised to AlphaCygni) is the star's designation...
apparent magnitude ranging from 0.05 to 0.18. It is classified as an AlphaCygnivariable due to the amplitude and periodicity of its brightness variation...
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was classified as a possible S Doradus variable. A 1998 paper considers it an active LBV, an AlphaCygnivariable, and a 2018 census of LBVs considers it...
December 15. It is slightly variable from magnitude 1.64 to 1.74, with no clear period, and it is classified as an α Cygnivariable. Its spectrum also varies...
A. M.; Sterken, C. (1999). "Light variations of massive stars (alphaCygnivariables). XVII. The LMC supergiants R 74 (LBV), R 78, HD 34664 = S 22 (B[e]/LBV)...
released his own accurately determined parallax for 61 Cygni in 1838. For this reason, Alpha Centauri is sometimes considered as the second star to have...
variations had been thought to be the due to the pulsations of an α Cygnivariable, but are too predictable and regular. The eclipse-like light curve is...
and diameter around 80 times that of the Sun. Classified as an AlphaCygni type variable star, Aludra varies in brightness from magnitude 2.38 to 2.48...
few million years.[citation needed] Eta CMa is classified as an AlphaCygni-type variable star and its brightness varies from magnitude +2.38 to +2.48 over...
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as AlphaCygnivariables, semiregular variables, and irregular variables show some degree of photometric variability, certain types of variables amongst...
visual magnitude between 4.87 and 4.98, and is suspected of being an AlphaCygnivariable, which are named after Deneb. It is in the same direction and at...
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96). In addition, it shows more irregular variations typical of an AlphaCygnivariable, irregularly pulsating hot supergiant stars. Mu Sagittarii A appears...
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to hundreds of days. The faster variations are characteristic of α Cygnivariables, irregular pulsating supergiants. The slower variations are accompanied...
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