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Astron. Astrophys. 364, 641-645 (2000)


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Detection of high-frequency optical oscillations on the flare star EV Lacertae

B.E. Zhilyaev 1,7, Ya.O. Romanyuk 1, I.A. Verlyuk 1, O.A. Svyatogorov 1, V.R. Khalack 1, A.V. Sergeev 2, R.K. Konstantinova-Antova 3,8, A.P. Antov 3,8, R.S. Bachev 3, I.Yu. Alekseev 4, V.E. Chalenko 4, D.N. Shakhovskoy 4, M.E. Contadakis 5 and S.J. Avgoloupis 6

1 National Academy of Sciences of Ukraine, Main Astronomical Observatory, Golosiiv, Kyiv-127, 03680, Ukraine (zhilyaev@mao.kiev.ua)
2 National Academy of Sciences of Ukraine, International Research Center for Astronomy, Medicine and Ecology, Golosiiv, Kyiv-127, 03680, Ukraine (sergeev@mao.kiev.ua)
3 Bulgarian Academy of Sciences, Institute of Astronomy, 72 Tsarigradsko shose, 1784 Sofia, Bulgaria (antovi@astro.bas.bg)
4 Crimean Astrophysical Observatory, Nauchny, Crimea 98409, Ukraine (ilya@crao.crimea.ua)
5 University of Thessaloniki, Department of Geodesy and Surveying, 54006 Thessaloniki, Greece (kodadaki@eng.auth.gr)
6 University of Thessaloniki, Department of Physics Section of Astrophysics, Astronomy and Mechanics, 54006 Thessaloniki, Greece (avgoloup@astro.auth.gr)
7 Isaac Newton Institute of Chile, Kiev Branch
8 Isaac Newton Institute of Chile, Bulgarian Branch

Received 10 May 2000 / Accepted 19 October 2000

Abstract

Many-site multichannel simultaneous observations of the flare star EV Lac revealed high-frequency brightness oscillations superimposed on the mean flare light curve. Oscillations occur at the earliest stage of a flare and are visible during the high state. Coherent oscillations of 26 and 13 sec were seen during three flare events. The pulsed fractions were 2.5% in the B band and 10-15% in the U band. This oscillatory phenomenon can be used to improve our understanding of the flare process.

Key words: stars: flare – stars: oscillations – stars: individual: EV Lac

Send offprint requests to: B.E. Zhilyaev

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001

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