Velocity distribution of interstellar H atoms in the heliospheric interface

In this paper we present first results of a numerical computation of the velocity distribution function of interstellar H atoms in the heliospheric interface, the region of the solar and interstellar wind interaction. The velocity distribution is a key tool to evaluate uncertainties introduced by various simplified models of the interface. We numerically solve the kinetic equation for gas of H-atoms self-consistently with the hydrodynamic equations for plasma. Neutral and plasma components are efficiently coupled by charge exchange. The interaction disturbs the atom velocity distribution, which is assumed to be Maxwellian in the circumsolar local interstellar medium. It is shown that besides 'original' interstellar atoms, there are three other important atom populations originating in the heliospheric interface. Velocity distribution functions of these populations at the heliopause are presented and discussed.