Tilt, Warp, and Simultaneous Precessions in Disks

Abstract

Warps are suspected in disks around massive compact objects. However, the proposed warping source -- non-axisymmetric radiation pressure -- does not apply to white dwarfs. In this letter we report the first Smoothed Particle Hydrodynamic simulations of accretion disks in SU UMa-type systems that naturally tilt, warp, and simultaneously precess in the prograde and retrograde directions using white dwarf V344 Lyrae in the Kepler field as our model. After ~79 days in V344 Lyrae, the disk angular momentum L_d becomes misaligned to the orbital angular momentum L_o. As the gas stream remains normal to L_o, hydrodynamics (e.g., the lift force) is a likely source to disk tilt. In addition to tilt, the outer disk annuli cyclically change shape from circular to highly eccentric due to tidal torques by the secondary star. The effect of simultaneous prograde and retrograde precession is a warp of the colder, denser midplane as seen along the disk rim. The simulated rate of apsidal advance to nodal regression per orbit nearly matches the observed ratio in V344 Lyrae.

3 figures, Letter

References in corpus (10)

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• Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae. V: The Fifth Year (2012-2013)
• The Emergence of Negative Superhumps in Cataclysmic Variables: Smoothed Particle Hydrodynamics Simulations
• The Shape of Long Outbursts in U Gem Type Dwarf Novae from AAVSO Data
• A 16-Year Photometric Campaign on the Eclipsing Novalike Variable DW Ursae Majoris
• Simplified models of circumstellar morphologies for interpreting high-resolution data. Analytical approach to the equatorial density enhancement
• Two-dimensional simulations of disks in close binaries: Simulating outburst cycles in cataclysmic variables
• OAO/MITSuME Photometry of Dwarf Novae: I SU Ursae Majoris
• Fuse and IUE Spectroscopy of the Prototype Dwarf Nova ER Ursa Majoris During Quiescence