A Lambda Eridani Variable is a class of
Be star
Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as ''classical Be stars'', is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer e ...
s that show small amplitude variations of a few hundredths of a magnitude. The variations are highly regular with periods between 0.5 and 2.0 days, and they were initially described as periodic Be stars.
Lambda Eridani
Lambda Eridani (λ Eri) is a star in the constellation Eridanus. It is visible to the naked eye on a dark night with an apparent visual magnitude of 4.27. The distance to this star, based upon an annual parallax shift of 0.00402 ...
is an example and the prototype. This has been ascribed to non-radial pulsations, inhomogeneous rotating discs, or the rotation of the star itself.
These stars are rarely classified, or are classified incorrectly. The
General Catalogue of Variable Stars does not have a type for λ Eridani variables, only GCAS for
Gamma Cassiopeiae variables and
BE for non-GCAS Be star variables. λ Eridani itself is incorrectly listed as a
Beta Cephei variable Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200, ...
.
The
AAVSO International Variable Star Index defines a LERI type of variability, with 16 stars included as λ Eri variables, five of them only suspected, and 13 combined with other types of variation.
References
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Star types