BY Draconis variable

BY Draconis variables are main sequence variable stars of late spectral types, usually K or M. The name comes from the archetype for this category of variable star system, BY Draconis. They exhibit variations in their luminosity due to rotation of the star coupled with star spots, and other chromospheric activity. Resultant brightness fluctuations are generally less that 0.5 magnitudes on timescales equivalent to the star's rotational period, typically from a fraction of a day to several months. Some of these stars may also have flares, resulting in additional variations of the UV Ceti type.

References

Samus N.N., Durlevich O.V., et al. Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.)

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