A star that varies noticeably in brightness; SYN. variable.
In astronomy, a star whose brightness changes, either regularly or irregularly, over a period ranging from a few hours to months or even years. The Cepheid variables regularly expand and contract in size every few days or weeks.
> Stars that change in size and brightness at less precise intervals include long-period variables, such as the red giant Mira in the constellation Cetus (period about 330 days), and irregular variables, such as some red supergiants. Eruptive variables emit sudden outbursts of light. Some suffer flares on their surfaces, while others, such as a nova, result from transfer of gas between a close pair of stars. A supernova is the explosive death of a star. In an eclipsing binary, the variation is due not to any change in the star itself, but to the periodic eclipse of a star by a close companion.