Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-02-14
Mon.Not.Roy.Astron.Soc. 325 (2001) 231
Astronomy and Astrophysics
Astrophysics
18 pages, 2 figures, to be published in MNRAS
Scientific paper
10.1046/j.1365-8711.2001.04416.x
A new theory of eccentric accretion discs is presented. Starting from the basic fluid-dynamical equations in three dimensions, I derive the fundamental set of one-dimensional equations that describe how the mass, angular momentum and eccentricity vector of a thin disc evolve as a result of internal stresses and external forcing. The analysis is asymptotically exact in the limit of a thin disc, and allows for slowly varying eccentricities of arbitrary magnitude. The theory is worked out in detail for a Maxwellian viscoelastic model of the turbulent stress in an accretion disc. This generalizes the conventional alpha viscosity model to account for the non-zero relaxation time of the turbulence, and is physically motivated by a consideration of the nature of magnetohydrodynamic turbulence. It is confirmed that circular discs are typically viscously unstable to eccentric perturbations, as found by Lyubarskij, Postnov & Prokhorov, if the conventional alpha viscosity model is adopted. However, the instability can usually be suppressed by introducing a sufficient relaxation time and/or bulk viscosity. It is then shown that an initially uniformly eccentric disc does not retain its eccentricity as had been suggested by previous analyses. The evolutionary equations should be useful in many applications, including understanding the origin of planetary eccentricities and testing theories of quasi-periodic oscillations in X-ray binaries.
No associations
LandOfFree
Non-linear fluid dynamics of eccentric discs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Non-linear fluid dynamics of eccentric discs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-linear fluid dynamics of eccentric discs will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-432565