OUTFLOW HYDRODYNAMICS IN THE ECLIPSING MILLISECOND PULSAR BINARIES PSR 1957+20 AND PSR 1744-24A

We present results of a two-dimensional calculation of the hydrodynamic wind outflow for the two eclipsing millisecond pulsar binaries PSR 1957 + 20 and PSR 1744-24A. The calculation includes pressure forces as an essential part of the wind hydrodynamics, and the wind material is assumed to be optically thick to pulsar radiation. We show that a shock forms where the gas outflowing from the companion star interacts with pulsar radiation. The eclipse shape is dependent on the possibly time-variable thermal and kinematic state of the outflowing gas. We present here results for a particular time chosen to represent important qualitative features of the outflow. The results of the simulations can be used to valuably constrain models for the formation of pulsar eclipses and mass outflow for star-vaporizing millisecond pulsars.