V. Izmodenov, Moscow State University

**Abstract.** 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.