Four-colour photometry of EY Dra: A study of an ultra-fast rotating active dM1-2e star

K. Vida, K. Oláh, Zs Kovári, J. Jurcsik, Á Sódor, M. Váradi, B. Belucz, I. Dékány, Zs Hurta, I. Nagy, K. Posztobányi

Research output: Contribution to journalArticle

9 Citations (Scopus)


We present more than 1000-day long photometry of EY Draconis in BV (RI)C passbands. The changes in the light curve are caused by the spottedness of the rotating surface. Modelling of the spotted surface shows that there are two large active regions present on the star on the opposite hemispheres. The evolution of the surface patterns suggests a flip-flop phenomenon. Using Fourier analysis, we detect a rotation period of Prot =0.45875 d, and an activity cycle with P ≈ 350 d, similar to the 11-year long cycle of the Sun. This cycle with its year-long period is the shortest one ever detected on active stars. Two bright flares are also detected and analysed.

Original languageEnglish
Pages (from-to)250-256
Number of pages7
JournalAstronomische Nachrichten
Issue number3
Publication statusPublished - Mar 1 2010



  • Activity-stars
  • Imaging-stars
  • Individual (EY Dra)-stars
  • Late-type-stars
  • Stars
  • Starspots

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this