extrinsic variable star
setâre-ye vartande-ye borungin
Fr.: étoile variable extrinsèque
A star whose variation in apparent brightness is not due to changes in the star itself but to some external cause, such as eclipsing by a companion.
Fr.: étoile variable
A star whose luminosity changes over periods of time; there are many reasons and many types. → cataclysmic variable; → Cepheid; → pulsating star; → nova; → long-period variable; → short-period variable; → Luminous Blue Variable (LBV); etc.
variable star designation
nâmgozini-ye setâre-ye vartandé
Fr.: designation des étoiles variables
A set of conventions used for naming variable stars. Stars with existing → Bayer designations are not given new designations. Alternatively, the letters R through Z are used followed by the Latin genitive of the name of the hosting constellation. Otherwise, two letters of alphabet are used (334 combinations) with the Latin genitive of the name of the constellation. Finally, the letter V (variable) is used followed by numbers 335, 336, and so on. Some examples are: → P Cygni, → T Tauri, → FU Orionis, → EX Lupi, and V509 Cassiopeiae.