Dissipative models of colliding stellar winds — I. Effects of thermal conduction in wide binary systems

The influence of electron thermal conduction on the 2D gas dynamics of colliding stellar winds is investigated. It is shown that, as a result of the non-linear dependence of the electron thermal flux on the temperature, the pre-heating zones (in which the hot gas in the interaction region heats the cool winds in front of the shocks) have finite sizes. The dependence of the problem of the structure of the flow in the interaction region on the dimensionless parameters is studied, and a simple expression is derived for the size of the pre-heating zones at the axis of symmetry. It is shown that small values of the thermal conductivity do not suppress the Kelvin–Helmholtz instability if the adiabatic flow is subject to it. Further studies, both numerical and analytical, in this direction will be of great interest. The influence of thermal conduction on the X-ray emission from the interaction region is also estimated.     

The spectral form of small-scale plasma turbulence in the auroral ionosphere

The spectra of amplitude fluctuations have been determined using 400 MHz transmissions from the Navy navigation satellite system (NNSS) observed at Spitsbergen. A spectrum model for electron density fluctuations is discussed. It is shown that a typical spectrum cut-off scale is l₀₁₁ ～5 + 15 km in the direction of the geomagnetic field.