An Etymological Dictionary of Astronomy and Astrophysics

A star that shows large irregular brightness variations and belongs to the Herbig Ae/Be family, i.e. pre-main sequence stars of intermediate mass. Typically a decrease of 2-3 magnitudes in the visible occurs for a few days to a couple of weeks. Current theories explain this behavior as being an obscuration of the central star by orbiting dust clouds, as well as contribution to the total luminosity by unsteady accretion onto the central star.
Also called UXOr.

See also: U and X letters of alphabet, Ori, → Orion; → star.