30,003 research outputs found
3D Finite Volume Simulation of Accretion Discs with Spiral Shocks
We perform 2D and 3D numerical simulations of an accretion disc in a close
binary system using the Simplified Flux vector Splitting (SFS) finite volume
method. In our calculations, gas is assumed to be the ideal one, and we
calculate the cases with gamma=1.01, 1.05, 1.1 and 1.2. The mass ratio of the
mass losing star to the mass accreting star is unity. Our results show that
spiral shocks are formed on the accretion disc in all cases. In 2D calculations
we find that the smaller gamma is, the more tightly the spiral winds. We
observe this trend in 3D calculations as well in somewhat weaker sense.Comment: 2 pages, LaTeX with 2 ps figures using crckapb.sty. To appear in the
Proceedings of Numerical Astrophysics 1998, Tokyo, Japan, 10-13 March, 1998,
eds. S. M. Miyama, K. Tomisaka and T. Hanawa (Kluwer Academic Publishers
Spiral Structure in IP Peg: Confronting Theory and Observations
The first convincing piece of evidence of spiral structure in the accretion
disc in IP Pegasi was found by Steeghs et al. (1997). We performed two kinds of
2D hydrodynamic simulations, a SFS finite volume scheme and a SPH scheme, with
a mass ratio of 0.5. Both results agreed well with each other. We constructed
Doppler maps and line flux-binary phase relations based on density
distributions, the results agreeing well with those obtained by observation.Comment: 4 pages, LaTeX with 2 ps figures using crckapb.sty. To appear in the
Proceedings of Numerical Astrophysics 1998, Tokyo, Japan, 10-13 March, 1998,
eds. S. M. Miyama, K. Tomisaka and T. Hanawa (Kluwer Academic Publishers
Proposal to observe the strong Van der Waals force in e+\bar{e} -> 2 \pi
Large discrepancy of the p-wave phase shift data of the
- scattering from those of the dispersion calculation is pointed out.
In order to determine which is correct, the pion form factor ,
which is the second source of information of the phase shift ,
is used. It is found that the phase shift obtained from the dispersion is not
compatible with the data of the pion form factor. What is wrong with the
dispersion calculation, is considered.Comment: 7 pages, 7eps figure
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