The Exact Solution of the Riemann Problem in Relativistic MHD

We discuss the procedure for the exact solution of the Riemann problem in special relativistic magnetohydrodynamics (MHD). We consider both initial states leading to a set of only three waves analogous to the ones in relativistic hydrodynamics, as well as generic initial states leading to the full set of seven MHD waves. Because of its generality, the solution presented here could serve as an important test for those numerical codes solving the MHD equations in relativistic regimes.Comment: 36 pages, 13 figures. Minor changes to match published versio

Parker Problem in Hall Magnetohydrodynamics

Parker problem in Hall magnetohydrodynamics (MHD) is considered. Poloidal shear into the toroidal flow generated by the Hall effect is incorporated. This is found to lead to a {\it triple deck} structure for the Parker problem in Hall MHD, with the magnetic field falling off in the intermediate Hall-resistive region more steeply (like \normalfont $1/x^3$) than that (like \normalfont$1/x$) in the outer ideal MHD region

Smoothed Particle Magnetohydrodynamics (some shocking results...)

There have been some issues in the past in attempts to simulate magnetic fields using the Smoothed Particle Hydrodynamics (SPH) method. SPH is well suited to star formation problems because of its Lagrangian nature. We present new, stable and conservative methods for magnetohydrodynamics (MHD) in SPH and present numerical tests on both waves and shocks in one dimension to show that it gives robust and accurate results.Comment: Kluwer latex, 6 pages, 3 figures; Proceedings of the International Workshop "Magnetic Fields and Star Formation: Theory vs Observations", Madrid, 21-25 April 2003. Revised version accepted to proceedings (exact solutions added, other minor changes