variable star

variable star

noun

Definition of VARIABLE STAR

:  a star whose brightness changes usually in more or less regular periods

First Known Use of VARIABLE STAR

1788

variable star

noun    (Concise Encyclopedia)

Star whose observed brightness varies noticeably in intensity. Pulsating variables expand and contract in cycles, pulsating rhythmically in brightness and size. Explosive variables include novas and supernovas, which brighten rapidly due to sudden outbursts of radiant energy; the increased brightness lasts a short time, followed by relatively slow dimming. Eclipsing variable stars are variable only because light from one star is blocked by another in Earth's direction. Hundreds of thousands of variable stars are known. See also binary star; Cepheid variable; flare star; pulsar; T Tauri star.