Is the accretion disc of TT Ari hotter after a minimum?

Tout, Christopher A.; Pringle, J. E.; Dous, C. La

doi:10.1093/mnras/265.1.l5

Cited by 7 publications

(6 citation statements)

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“…The literature on the SW Sex phenomenon has been rapidly expanding in recent years. The original theory of an accretion disc wind (Honeycutt, Schlegel & Kaitchuck 1986) and its variants (Dhillon & Rutten 1995;Murray & Chiang 1996) have been followed by theories of Stark broadening (Lin, Williams & Stover 1988), magnetically driven inflows (Williams 1989), outflows (Tout, Pringle & la Dous 1993;Wynn, King & Horne 1995) and bright-spot overflows (Hellier & Robinson 1994;Hellier 1996). Judging by the results of our Doppler tomography experiments (section 4.8), it seems that, in the case of SW Sex at least, a much more simple model will suffice.…”

Section: Discussionmentioning

confidence: 99%

On the nature of SW Sex

Dhillon

Marsh

Jones

1997

Monthly Notices of the Royal Astronomical Society

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We present spectrophotometry of the eclipsing nova-like variable SW Sex. The continuum is deeply eclipsed and shows asymmetries due to the presence of a bright spot. We derive a new ephemeris and, by measuring the eclipse width, we are able to constrain the inclination to i > 75 • and the disc radius to R D > 0.6L 1 . In common with other members of its class (of which it is the proto-type), SW Sex shows single-peaked emission lines which show transient absorption features and large phase shifts in their radial velocity curves. In addition, the light curves of the emission lines show a reduction in flux around phase 0.5 and asymmetric eclipse profiles which are not as deep as the continuum eclipse. Using Doppler tomography, we find that most of the line emission in SW Sex appears to originate from three sources: the secondary star, the accretion disc and an extended bright spot. The detection of the red star allows us to constrain the radial-velocity semi-amplitude of the secondary to K R > 180 km s −1 and hence the component masses toThe Doppler maps suggest a simple new model for SW Sex in which the dominance of single-peaked line emission from the bright spot over the weak double-peaked disc emission gives SW Sex its single-peaked profiles and forces the radial-velocity curves to follow the motion of the bright spot and thus exhibit large phase shifts. The transient absorption features in the Balmer-line profiles are mostly artifacts of the complex intertwining of the emission components from the secondary star, bright spot and accretion disc and involve little true absorption. While the accretion disc and secondary star components of this model appear to be secure, the dominant bright-spot component fails in one important area -its inconsistency with the Balmer-line light curves. The eclipse profile requires the material emitting the Balmer lines to be eclipsed as early as phase 0.8, but which is not as deeply eclipsed as the continuum, exhibits a flat bottomed eclipse and then comes out of eclipse very sharply around phase 0.05. Although it is possible to explain the early ingress with a raised disc rim downstream from the bright-spot, the rapid egress is difficult to account for without speculating that either there are regions of strong Balmer absorption in the disc whose changing visibility during eclipse alters the shape of the light curve or that there is Balmer emission from above the orbital plane which shares the velocity of the bright-spot.

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Section: Discussionmentioning

confidence: 99%

On the nature of SW Sex

Dhillon

Marsh

Jones

1997

Monthly Notices of the Royal Astronomical Society

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“…It is important to note that while current MHD simulations are generally incapable of following in detail the process of large-scale poloidal field generation, the most recent numerical results (Turner, Bodenheimer & Rozyczka 1999;Kudoh, Matsumoto & Shibata 2002) give some credence to the jet production process we propose. The concept that an accretion disk in a nova-like variable can switch as time proceeds from being initially a standard radiative disk to being one in which it releases less of its energy thermally finds some support in the observations of the anti-dwarf nova TT Ari before and after a short minimum (Tout, Pringle, & la Dous 1993). Recent computations on driving outflows in the nova-like variables IX Vel and V3885 Sgr also indicate the need for magnetic driving (Hartley et al 2002).…”

Section: The Two Statesmentioning

confidence: 99%

The Disk‐Jet Connection in Microquasars and Active Galactic Nuclei

Livio

Pringle

King

2003

ApJ

Self Cite

108

114

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We propose a new model for the disk-jet connection in black hole x-ray transients and active galactic nuclei. In our model, the inner part of the accretion disk around the central black hole switches between two states. In one state, the accretion energy is dissipated locally (some within the disk, some within a corona) to produce the observed disk luminosity. In the second state, the accretion energy is deposited into the bulk flow of a relativistic jet. We associate the transition between the two states with the generation of a global, poloidal magnetic field. We show that this model can explain the observed behavior of black hole accretors.

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“…It may be natural to assume that after the disk has returned from its temporary low state it takes some time before the magnetic angular momentum transport works, and that during this interval the disk emits more thermal radiation, that is it appears to be hotter and bluer than normally. Tout et al (1993) find evidence in archived IUE observations that the disk is bluer after a minimum in 1981 than before the same minimum.…”

Section: A Challenge For Observersmentioning

confidence: 71%

“…An even more intricate argument forms the basis for the interpretation of the spectral variations in TT Ari (Tout et al 1993). TT Ari is a so-called anti-dwarf nova, that from time to time decreases in luminosity by a few magnitudes.…”

Section: A Challenge For Observersmentioning

confidence: 99%

Magnetohydrodynamic instabilities and turbulence in accretion disks

Schramkowski

Torkelsson

1996

The Astron Astrophys Rev

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In this paper we review the possibilities for magnetohydrodynamic processes to handle the angular momentum transport in accretion disks. Traditionally the angular momentum transport has been considered to be the result of turbulent viscosity in the disk, although the Keplerian flow in accretion disks is linearly stable towards hydrodynamic perturbations. It is on the other hand linearly unstable to some magnetohydrodynamic (MHD) instabilities. The most important instabilities are the Parker and Balbus-Hawley instabilities that are related to the magnetic buoyancy and the shear flow, respectively. We discuss these instabilities not only in the traditional MHD framework, but also in the context of slender flux tubes, that reduce the complexity of the problem while keeping most of the stability properties of the complete problem. In the non-linear regime the instabilities produce turbulence. Recent numerical simulations describe the generation of magnetic fields by a dynamo in the resulting turbulent flow. Eventually such a dynamo may generate a global magnetic field in the disk. The relation of the MHD-turbulence to observations of accretion disks is still obscure. It is commonly believed that magnetic fields can be highly efficient in transporting the angular momentum, but emission lines, short-time scale variability and non-thermal radiation, which a stellar astronomer would take as signs of magnetic variability, are more commonly observed during periods of low accretion rates.

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Is the accretion disc of TT Ari hotter after a minimum?

Cited by 7 publications

References 0 publications

On the nature of SW Sex

On the nature of SW Sex

The Disk‐Jet Connection in Microquasars and Active Galactic Nuclei

Magnetohydrodynamic instabilities and turbulence in accretion disks

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