Lambda Eridani variable explained

A Lambda Eridani Variable is a class of Be stars 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.^[1] Lambda Eridani is an example and the prototype. This has been ascribed to non-radial pulsations, inhomogeneous rotating discs, or the rotation of the star itself.^{[2] [3]}

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.^[4] The AAVSO International Variable Star Index defines a LERI type of variability, with 51 stars included as λ Eri variables, 16 of them only suspected, and 32 combined with other types of variation.^{[5] [6]}

Notes and References

1. 1995MNRAS.277.1547B. Tests of the Pulsation and Starspot Models for the Periodic Be-Stars. Monthly Notices of the Royal Astronomical Society. 277. 4. 1547–1554. Balona. L. A. 1995. 10.1093/mnras/277.4.1547. free.
2. 2011AcA....61..247J. 1110.4064. A CCD Search for Variable Stars of Spectral Type B in the Northern Hemisphere Open Clusters. VIII. NGC 6834. Acta Astronomica. 61. 247–273. Jerzykiewicz. M.. Kopacki. G.. Pigulski. A.. Kołaczkowski. Z.. Kim. S.-L.. 2011. 3.
3. 10.1051/0004-6361:20020174. Search for duplicity in periodic variable Be stars. Astronomy and Astrophysics. 385. 2. 488. 2002. Carrier. F.. Burki. G.. Burnet. M.. 2002A&A...385..488C . free.
4. 2009yCat....102025S. VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013). VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. etal. Samus. N. N.. Durlevich. O. V.. 2009.
5. Web site: Variable Star Type Designations in the VSX. Otero. S. A. . Watson . C. . Wils . P. . AAVSO Website. American Association of Variable Star Observers. 19 July 2014.
6. 2015yCat....102027W. VizieR Online Data Catalog: AAVSO International Variable Star Index VSX (Watson+, 2006-). VizieR On-line Data Catalog: B/VSX. Originally Published in: 2006SASS...25...47W. 1. etal. Watson. C. . Henden. A. A.. 2022 . 8 March 2024.