On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field.

Details On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field. On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field.

Jan 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996a%26a...305..359s&link_type=abstract

Astronomy and Astrophysics, v.305, p.359

Astronomy and Astrophysics

Astrophysics

7

Mhd, Instabilities, Stars: Formation

Scientific paper

A family of solutions of the equilibrium equation of rotating infinitely thin polytropic discs with a two - dimensional pressure acting in the plane of the disc and a poloidal magnetic field is presented. Both the surface density and the magnetic field in the midplane are simple power laws. Their exponent depends on the polytropic index. These solutions represent self - consistent equilibrium states. The integrodifferential equation of adiabatic axisymmetric perturbations is derived. For marginally stable perturbations, the solution of this equation can be given in closed form. As the existence of marginally stable perturbations indicates instability, the behaviour of such perturbations is discussed. We consider the dependence of the stability on the magnetic field for a disc with given mass and angular momentum. Since all polytropic discs behave like the isothermal disc, only this disc is studied in detail. For arbitrary magnetic fields the isothermal disc is unstable against axisymmetric perturbations with an adiabatic exponent 0<γ<0.75 . Here, the magnetic field reinforces the instability. Stability against axisymmetric perturbations is possible only for perturbations with γ>=0.75. With an increase of the magnetic field the stable discs pass to unstable ones. If the magnetic field exceeds an upper limit, all discs are unstable. The comparison of the results with those of a rigidly rotating homogeneous disc shows striking differences. These differences stem from the fact that the homogeneous disc is a singular model.

Affiliated with

Also associated with

No associations

Rating

On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field. 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 On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and On the stability of rotating self - gravitating polytropic discs with a poloidal magnetic field. will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-966957