Journal Article

Atlas of tilted accretion discs and source to negative superhumps

M. M. Montgomery

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 4, pages 1897-1907
Published in print April 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14487.x
Atlas of tilted accretion discs and source to negative superhumps

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Using smoothed particle hydrodynamics, we numerically simulate steady-state accretion discs for cataclysmic variable dwarf novae systems that have a secondary-to-primary mass ratio 0.35 ≤q≤ 0.55. After these accretion discs have come to quasi-equilibrium, we rotate each disc out of the orbital plane by δ= (1, 2, 3, 4, 5 or 20)° to induce negative superhumps. For accretion discs tilted 5°, we generate light curves and associated Fourier transforms for an atlas on negative superhumps and retrograde precession. Our simulation results suggest that accretion discs need to be tilted more than 3° for negative superhumps to be statistically significant. We also show that if the disc is tilted enough such that the gas stream strikes a disc face, then a dense cooling ring is generated near the radius of impact.

In addition to the atlas, we study these artificially tilted accretion discs to find the source to negative superhumps. Our results suggest that the source is additional light from innermost disc annuli, and this additional light waxes and wanes with the amount of gas stream overflow received as the secondary orbits. The nodes, where the gas stream transitions from flowing over to under the disc rim (and vice versa), precess in the retrograde direction.

Keywords: accretion, accretion discs; hydrodynamics; methods: numerical; binaries: close; novae, cataclysmic variables

Journal Article.  9524 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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