The subcritical baroclinic instability in local accretion disc models

Details The subcritical baroclinic instability in local accretion disc models The subcritical baroclinic instability in local accretion disc models

2009-11-03

arxiv.org/abs/0911.0663v2

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

12 pages, 17 figures, Accepted in A&A

Scientific paper

(abridged) Aims: We present new results exhibiting a subcritical baroclinic instability (SBI) in local shearing box models. We describe the 2D and 3D behaviour of this instability using numerical simulations and we present a simple analytical model describing the underlying physical process. Results: A subcritical baroclinic instability is observed in flows stable for the Solberg-Hoiland criterion using local simulations. This instability is found to be a nonlinear (or subcritical) instability, which cannot be described by ordinary linear approaches. It requires a radial entropy gradient weakly unstable for the Schwartzchild criterion and a strong thermal diffusivity (or equivalently a short cooling time). In compressible simulations, the instability produces density waves which transport angular momentum outward with typically alpha<3e-3, the exact value depending on the background temperature profile. Finally, the instability survives in 3D, vortex cores becoming turbulent due to parametric instabilities. Conclusions: The subcritical baroclinic instability is a robust phenomenon, which can be captured using local simulations. The instability survives in 3D thanks to a balance between the 2D SBI and 3D parametric instabilities. Finally, this instability can lead to a weak outward transport of angular momentum, due to the generation of density waves by the vortices.

Affiliated with

Also associated with

No associations

Rating

The subcritical baroclinic instability in local accretion disc models 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 The subcritical baroclinic instability in local accretion disc models, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The subcritical baroclinic instability in local accretion disc models will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-618694