Doppler signatures of Hα flares in AE Aquarii |
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| Authors: | William F Welsh Keith Horne & Richard Gomer |
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| Institution: | The University of Texas, Department of Astronomy, Austin, TX 78712, USA,;Keele University, Department of Physics, Keele, Staffordshire ST5 5BG,;University of St. Andrews, School of Physics and Astronomy, North Haugh, St. Andrews, Fife KY16 9SS,;Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251-1892, USA |
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| Abstract: | We present high-speed spectrophotometric observations of the Hα emission in the exotic cataclysmic variable AE Aqr. Over 10 000 spectra with a sampling rate of ～ 6 s were obtained. The well-known 16.5- and 33-s oscillations were not detected in either the continuum or the line, nor were any quasi-periodic oscillations detected. The Hα line shows remarkably complex behaviour, with changes in flux of up to a factor of 3 in a few hours. The line does not act as a single entity — the instantaneous line profile is highly asymmetric and consists of a superposition of emission components that are localized in velocity. We find that during flares the Hα emission is delayed and decays more slowly than the continuum. The Hα variations are not linearly correlated with the continuum variations. Examination of the trailed spectrograms and Doppler tomograms reveals no signatures of an accretion disc, but rather supports the idea that mass is being ejected by a propeller mechanism. |
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| Keywords: | accretion accretion discs binaries: close stars: individual: AE Aqr novae cataclysmic variables stars: oscillations |
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