Rotating ellipsoidal variables are a class of

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 ...

. They are close

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that t ...

systems whose components are

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

al. They are not eclipsing, but fluctuations in

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

occur due to changes in the amount of light emitting area visible to the observer. Typical brightness fluctuations do not exceed 0.1 magnitudes. The brightest rotating ellipsoidal variable is

Spica Spica is the brightest object in the constellation of Virgo and one of the 20 brightest stars in the night sky. It has the Bayer designation α Virginis, which is Latinised to Alpha Virginis and abbreviated Alpha Vir or α Vir. Analys ...

(α Virginis).

References

* Morris, S.L. "The Ellipsoidal Variable Stars", ApJ 295: 143–152, 1985 August 1 * Samus N.N., Durlevich O.V., et al. ''Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.)'' * Variable stars * {{var-star-stub