Tags: Star.
EF Eridani (abbreviated EF Eri sometimes incorrectly referred to as EF Eridanus) is a variable star of the type known as polars AM Herculis stars or magnetic cataclysmic variable stars. Historically it has varied between apparent magnitudes 14.5 and 17.3 although since 1995 it has generally remained at the lower limit. The star system consists of a white dwarf star with a substellar massed former star in orbit.