The V-EUV Delay for Dwarf Nova Outbursts: A Case Study for VW Hydri, U Geminorum, and SS Cygni

Abstract

We present a parameter study using time dependent calculations of the thermal limit cycle model for dwarf nova outbursts. Our goal is to delineate the dependence of the delay between the initial rapid rise of the visual and EUV fluxes during the start of an outburst on model parameters, concentrating on three bright, nearby systems for which complete optical and EUV observations exist - VW Hyi, U Gem, and SS Cyg. For these systems we infer that the outburst must be triggered at ~0.7-0.8 of the outer disk radius to produce delays which are in accord with observations. We also see a stagnation or period of slow warming (first noted by Mineshige) during the early stages of thermal instability, but find it does not influence the V-EUV delay since it precedes the rapid rise in V at the start of the outburst. We find that if one decreases the surface density in the inner disk, interior to the instigation radius, the V-EUV delay can be lengthened by as much as a factor of two. In addition, we find there to be a weak relation between the V-EUV delay and the value of the alpha viscosity parameter in quiescence.

30 pages, 12 Postscript figures, ApJ, v. 556 (2001 Aug 1)

References in corpus (4)

• Linear Analysis of the Hall Effect in Protostellar Disks
• The nature of dwarf nova outbursts
• Viscosity Mechanisms in Accretion Disks
• The Outbursts of Dwarf Novae

Cited by in corpus (19)

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• On the physical nature of accretion disc viscosity
• The Kepler light curves of V1504 Cygni and V344 Lyrae: A study of the Outburst Properties
• Blandford-Znajek jets in galaxy formation simulations: method and implementation
• The Kepler Light Curve of V344 Lyrae: Constraining the Thermal-Viscous Limit Cycle Instability
• Delays in dwarf novae I: The case of SS Cygni
• Delays in dwarf novae: VW Hyi, the tidal instability and enhanced mass transfer models
• The 2001 Superoutburst of WZ Sagittae: A Clue to the Dynamics of Accretion Disks
• Two-dimensional models of layered protoplanetary discs - II. The effect of a residual viscosity in the dead zone
• The October 1985 Long Outburst of U Geminorum: Revealing the Viscous Time Scale in Long Orbital Period Dwarf Novae
• Modeling Eclipses in the Classical Nova V Persei: The Role of the Accretion Disk Rim
• Spin measurement of 4U 1543-47 with Insight-HXMT and NICER from its 2021 outburst: A test of accretion disk models at high luminosities
• Multiwavelength monitoring of a very active dwarf nova AX J1549.8$-$5416 with an unusually high duty cycle
• The dependence of the viscosity-parameter on the disk scale height profile
• Challenging the disk instability model: I -- The case of YZ LMi
• Mass-transfer Outburts reborn: Modeling the light curve of the dwarf nova EX Draconis