Gas dynamics of semidetached binaries

Lubow, S. H.; Shu, Frank H.

doi:10.1086/153614

Cited by 583 publications

(473 citation statements)

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“…Equation (5) is a fit to Lubow & Shu (1975) Table 2; this fit is accurate to better than 1% for 0.06 < q < 1. This implies that ifṀ tr <Ṁ A (1.5r circ ), there exists a magnetic moment for which the disc can be stable; otherwise, the system is either unstable or has no disc.…”

Section: Stability Criteriamentioning

confidence: 93%

Dwarf nova outbursts in intermediate polars

Hameury

Lasota

2017

A&A

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Context. The disc instability model (DIM) has been very successful in explaining the dwarf nova outbursts observed in cataclysmic variables. When, as in intermediate polars, the accreting white dwarf is magnetised, the disc is truncated at the magnetospheric radius, but for mass-transfer rates corresponding to the thermal-viscous instability such systems should still exhibit dwarf-nova outbursts. Yet, the majority of intermediate polars, in which the magnetic field is not large enough to completely disrupt the accretion disc, seem to be stable, and the rare observed outbursts, in particular in systems with long orbital periods, are much shorter than normal dwarf-nova outbursts. Aims. We investigate the predictions of the disc instability model for intermediate polars in order to determine which of the observed properties of these systems can be explained by the DIM. Methods. We use our numerical code for the time evolution of accretion discs, modified to include the effects of the magnetic field, with constant or variable mass transfer from the secondary star. Results. We show that intermediate polars have mass transfer low enough and magnetic fields large enough to keep the accretion disc stable on the cold equilibrium branch. We show that the infrequent and short outbursts observed in long-period systems, such as, for example, TV Col, cannot be attributed to the thermal-viscous instability of the accretion disc, but instead have to be triggered by an enhanced mass-transfer from the secondary, or, more likely, by some instability coupling the white dwarf magnetic field with that generated by the magnetorotational instability operating in the accretion disc. Longer outbursts (a few days) could result from the disc instability.

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Section: Stability Criteriamentioning

confidence: 93%

Dwarf nova outbursts in intermediate polars

Hameury

Lasota

2017

A&A

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“…If matter from one star reaches this saddle point, known as the inner Lagrangian point, or L1, then it can accrete onto the other star. Since there is relative motion between the stars, however, the overflowing matter cannot strike the accreting star directly, but rather goes into an orbit [45] dictated by its specific angular momentum. If sufficiently large quantities of matter spill through L1, however, these orbits cannot persist.…”

Section: Accretion Disksmentioning

confidence: 99%

Atomic X-ray spectroscopy of accreting black holes

Liedahl¹,

Torres²

2005

Can. J. Phys.

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Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy. PACS Nos.: 32.30. Rj, 32.80.Hd, 95.30.Dr, 95.30.Sf, 95.85.Nv, 97.10.Gz. 97.80.Jp, 98.35.Mp, 98.62.Mw

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“…Presently there is no evidence to doubt Case (a). The mass penetration through the vicinities of the inner Lagrangian point was discussed in detail by Lubow and Shu (1975) . The presence of a magnetic field affects also the structure of the transition zone between the Roche lobes of the compenents.…”

Section: Zone B: 'Propeller' or 'Pendulum'?mentioning

confidence: 99%

‘Swinging Dipoles’ in Magnetic Close Binary Stars

Андронов

1987

International Astronomical Union Colloquium

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ABSTRACT. The recently discovered phenomena in polars -Magnetic Close Binary Stars (MCBS) , are discussed. Asynchronous MCBS are on the 'propeller stage' (which is analogous to the investigated one for neutron stars), and are synchronizing during t s < 10 3 yr, being during this stage rapidly evolving, mass ejecting systems. The accretion rate is largest when the angle 9 between the magnetic axis and the line of centers is near zero. If 9 «• 90°, then the magnetic field prevents the plasma flow, and the 'magnetic valve' becomes closed. Near this position the oscillations of the orientation of the white dwarf's magnetic axis may be excited. This model of a 'swinging dipole' has such observational properties: (a) the system's luminosity changes with characteristical times of some years; (b) the phase curves of light, polarization and radial velocities must be cyclically changing with a few year cycle; (c) one would observe the correlation between the phase shift of these curves, and the system's luminosity. The observational data on polars are briefly discussed. All these phenomena are observed in AM Herculis and some other polars, but subsequent studies are needed to investigate the orientation changes of the magnetic axis, and so the structure and evolution of this exotic class of our Galaxy population.

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Gas dynamics of semidetached binaries

Cited by 583 publications

References 0 publications

Dwarf nova outbursts in intermediate polars

Dwarf nova outbursts in intermediate polars

Atomic X-ray spectroscopy of accreting black holes

‘Swinging Dipoles’ in Magnetic Close Binary Stars

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