Origin of ultraviolet emission source in the Jovian ionosphere at the feetof the Io flux tube

A model for an explanation of far ultraviolet (FUV) emissions observed from the Io flux tube footprints at the Jovian ionosphere is presented. An acce leration of electrons and ions of the ionospheric plasma up to sufficient e nergies for ail effective excitation of H-2 Lyman and Werner bands is propo sed. The neutral particles within the Jovian ionosphere are excited due to their collisions with the charged particles relatively moving to the neutra ls in the ionospheric plasma. The motion is induced by the Ampere force whi ch arises due to the interaction between the electric current flowing withi n the lo magnetic flux tube and its own specific magnetic field. It is esta blished that only a sufficiently strong field-aligned current. is capable o f providing the required velocity of the relative motion. Our estimates sho w that in principle the proposed mechanism can provide the level of FUV emi ssions observed from the Io flux tube footprints.