Accretion stream mapping of HU Aquarii |
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Authors: | Sonja Vrielmann Axel D Schwope |
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Institution: | Department of Astronomy, University of Cape Town, Private Bag, Rondebosch, 7700, South Africa;Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany |
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Abstract: | We present a new mapping algorithm, the Accretion Stream Mapping (ASM), which uses the full phase-coverage of a light curve to derive spatially resolved intensity distributions along the accretion stream in magnetic cataclysmic variables of AM Herculis type (polars). The surface of the accretion stream is approximated as a 12-sided (duodecadon-shaped) tube. After successfully testing this method on artificial data we applied it to emission-line light curves of H β , H γ and He ii λ 4686 of the bright eclipsing polar HU Aqr. We find hydrogen and helium line emission bright in the threading region of the stream where the stream couples on to magnetic field lines. It is particularly interesting that the stream is bright on the irradiated side facing the white dwarf, which highlights the interplay of collisional and radiative excitation/ionization. |
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Keywords: | accretion accretion discs binaries: eclipsing stars: individual: HU Aqr novae cataclysmic variables |
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