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Astro*Dictionary by Michael Erlewine





1 article for "Semi-Regular Variable"

Semi-Regular Variable [Astro*Index]

Also called SR variables.

A group of giant and supergiant pulsating variables with variations of only 1 or 2 magnitudes, ranging from a few days to several years. Four subgroups are recognized: SRa and SRb Variables are giants (late spectral types M, C, and S); the SRa-types have relatively stable periods, but the periods for SRb- types are not well defined, and are easily confused with Mira Variables. Red supergiants of late spectral types (Antares, Betelgeuse, and Mu Cephei) characterize the SRc Variables; and the SRd Variables are highly luminous yellow supergiants and giants (F, G, and K spectral types).

See also:
♦ Spectral Class ♦ Giant Star ♦ Magnitude


Astro*Index Copyright © 1997 Michael Erlewine