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Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables – II. A low-inertia magnetic accretor model

Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables – II. A low-inertia magnetic accretor model
Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables – II. A low-inertia magnetic accretor model
The dwarf nova oscillations observed in cataclysmic variable (CV) stars are interpreted in the context of a low-inertia accretor model, in which accretion on to an equatorial belt of the white dwarf primary causes the belt to vary its angular velocity. The rapid deceleration phase is attributed to propellering. Evidence that temporary expulsion rather than accretion of gas occurs during this phase is obtained from the large drop in extreme ultraviolet flux.
We show that the quasi-periodic oscillations are most probably caused by a vertical thickening of the disc, moving as a travelling wave near the inner edge of the disc. This alternately obscures and ‘reflects’ radiation from the central source, and is visible even in quite low inclination systems. A possible excitation mechanism, caused by winding up and reconnection of magnetic field lines, is proposed.
We apply the model, deduced largely from VW Hyi observations, to re-interpret observations of SS Cyg, OY Car, UX UMa, V2051 Oph, V436 Cen and WZ Sge. In the last of these we demonstrate the existence of a 742-s period in the light curve, arising from obscuration by the travelling wave, and hence show that the two principal oscillations are a dwarf nova oscillation and its reprocessed companion.
accretion, accretion discs, stars: individual: VW Hyi, stars: individual: WZ Sge, stars: individual: V2051 Oph, novae, cataclysmic variables, stars: oscillations
1365-2966
84-98
Warner, Brian
0121587e-9b0d-423a-9579-c9b45487629b
Woudt, Patrick A.
078a12fd-3894-42c5-b3b6-1747a9325c51
Warner, Brian
0121587e-9b0d-423a-9579-c9b45487629b
Woudt, Patrick A.
078a12fd-3894-42c5-b3b6-1747a9325c51

Warner, Brian and Woudt, Patrick A. (2002) Dwarf nova oscillations and quasi-periodic oscillations in cataclysmic variables – II. A low-inertia magnetic accretor model. Monthly Notices of the Royal Astronomical Society, 335 (1), 84-98. (doi:10.1046/j.1365-8711.2002.05596.x).

Record type: Article

Abstract

The dwarf nova oscillations observed in cataclysmic variable (CV) stars are interpreted in the context of a low-inertia accretor model, in which accretion on to an equatorial belt of the white dwarf primary causes the belt to vary its angular velocity. The rapid deceleration phase is attributed to propellering. Evidence that temporary expulsion rather than accretion of gas occurs during this phase is obtained from the large drop in extreme ultraviolet flux.
We show that the quasi-periodic oscillations are most probably caused by a vertical thickening of the disc, moving as a travelling wave near the inner edge of the disc. This alternately obscures and ‘reflects’ radiation from the central source, and is visible even in quite low inclination systems. A possible excitation mechanism, caused by winding up and reconnection of magnetic field lines, is proposed.
We apply the model, deduced largely from VW Hyi observations, to re-interpret observations of SS Cyg, OY Car, UX UMa, V2051 Oph, V436 Cen and WZ Sge. In the last of these we demonstrate the existence of a 742-s period in the light curve, arising from obscuration by the travelling wave, and hence show that the two principal oscillations are a dwarf nova oscillation and its reprocessed companion.

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More information

Published date: September 2002
Keywords: accretion, accretion discs, stars: individual: VW Hyi, stars: individual: WZ Sge, stars: individual: V2051 Oph, novae, cataclysmic variables, stars: oscillations

Identifiers

Local EPrints ID: 47047
URI: http://eprints.soton.ac.uk/id/eprint/47047
ISSN: 1365-2966
PURE UUID: 5e2d9429-abc4-44e2-b645-f2428613aac8

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Date deposited: 24 Jul 2007
Last modified: 15 Mar 2024 09:29

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Author: Brian Warner
Author: Patrick A. Woudt

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