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Paper: SPH Simulations of the 2:1 Resonance in Accretion Disks
Volume: 330, The Astrophysics of Cataclysmic Variables and Related Objects
Page: 389
Authors: Kunze, S.; Speith, R.
Abstract: In systems with very low-mass secondaries the radius of the 2:1 resonance can lie within the Roche lobe of the primary. Disk matter at this radius will orbit around the primary exactly twice during one orbit of the secondary. Osaki & Meyer (2002) suggested that the early humps in WZ Sagittae superoutbursts are linked to this 2:1 resonance. Our Smoothed Particle Hydrodynamics (SPH) simulations confirm that the resonance leads to a two-armed spiral feature at the outer rim of the disk, as first discussed by Lin & Papaloizou (1979). Unlike the effect of the 3:1 resonance – the slow prograde precession of an eccentric disk, visible as superhumps during the superoutbursts of SU UMa stars – these spiral arms are fixed in the co-rotating frame of reference. The tidal dissipation in these arms leads to a double-peaked feature in the orbital light curve, when viewed at high inclination, just as it is the case with WZ Sge.
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