Similarities and Differences Between the Light Variability of the K Giant and Dwarf Active Binaries HK Lac and BY Dra

Part of the NATO ASI Series book series (ASIC, volume 319)


The long term light and color (B-V, U-B) variations of BY Dra and HK Lac are discussed. Cyclic behaviour of the visual and U-B color variation of HK Lac has been found with a period of 5.4 years, showing 0.3 phase shift between the V(mean) and U-B cycles. A possible explanation of the feature is given.


Color Variation Cyclic Behaviour Spot Activity Chromospheric Activity Poster Paper 
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  1. Dorren, J.D., Guinan, E.F., 1989, Astrophys. J., in press.Google Scholar
  2. Olah, K., 1989, Proc. IAU Coll. No. 104 (Solar and Stellar Flares, ed. by B.M. Haisch and M. Rodono), Poster Papers, Catania Special Publ, p. 135.Google Scholar
  3. Olah, K., Hall, D.S., 1988, Comm. Konkoly Observatory, No. 91 (Vol. 10, Part 5), p. 121.Google Scholar
  4. Poe, C.H., Eaton, J.A., 1985, Astrophys. J. 289. 644.ADSCrossRefGoogle Scholar
  5. Strassmeier, K.G., Hall, D.S., Zeilik, M., Nelson, E., Eker, Z., Fekel, F.C., 1988, Astron. Astrophys. Suppl. 72. 291.ADSGoogle Scholar
  6. Vogt, S.S., Fekel, F., 1979, Astrophys. J. 234. 958.ADSCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • K. Olah
    • 1
  1. 1.Konkoly ObservatoryBudapestHungary

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