Selected results -3D MHD Simulations of Disk Accretion to an Inclined Dipole: Radiative Shock

Recent papers on astro-ph

Wind Accretion to Dipole
- Bondi accretion
- Isolated old NS
- Propeller stage
- Magneto t a i l s

Disk Accretion to Dipole
- Inclined   rotator
- F u n n e l flows
- Propeller   stage
- Hot spots on star
- Radiative   shock

The Origin of Jets

Accretion Disks Theory
- Counterrotating
- ADAF theory

Extrasolar Planets

DISK ACCRETION TO MAGNETIZED STARS

OSCILLATIONS OF MHD SHOCK WAVES ON THE SURFACES OF T-TAURI STARS

[abstract] [plots from the paper] [animation] [full text]

This work treats the matter deceleration in a magnetohydrodynamics radiative shock wave at the surface of a star.

The problem is relevant to classical T Tauri stars where infalling matter is channeled along the star’s magnetic field and stopped in the dense layers of photosphere. A significant new aspect of the present work is that the magnetic field has an arbitrary angle with respect to the normal to the star’s surface.

We consider the limit where the magnetic field at the surface of the star is not very strong in the sense that the inflow is super Alfvenic.

In this limit the initial deceleration and heating of plasma (at the entrance to the cooling zone) occurs in a fast magnetohydrodynamic shock wave. To calculate the intensity of radiative losses we use “real” and “power-law” radiative functions.

We determine the stability/instability of the radiative shock wave as a function of parameters of the incoming flow: velocity, strength of the magnetic field, and its inclination to the surface of the star.
In a number of simulation runs with the “real” radiative function, we find a simple criterion for stability of the radiative shock wave. For a wide range of parameters, the periods of oscillation of the shock wave are of the order 0.02 − 0.2 s.