An Etymological Dictionary of Astronomy and Astrophysics

A member of a class of → pre-main sequence stars that experience dramatic changes in magnitude and → spectral type. During an outburst the luminosity of such an object can increase by several orders of magnitude on short time-scales (few months to few years). The phenomenon is explained by abrupt mass transfer from an → accretion disk to a young, low mass → T Tauri star (accretion rates 10^-4 to 10^-3 solar masses per year). → EX Lupi; → Z CMa.

See also: F and U, alphabet letters; Orionis, → Orion; → object.