Bahamida, SaidaAnnou, K.Annou, R.2016-02-042016-02-042007978-162276334-4https://dspace.univ-boumerdes.dz/handle/123456789/2658Electron-positron plasmas are believed to exist in the early universe, in active galactic nuclei, and in pulsar magnetospheres. Most of the astrophysical plasmas usually contain ions as well in addition to electrons and positrons. In this work, the ion-acoustic solitons are investigated in three-component plasmas, whose constituents are inertial ions, nonthermal electrons, and Boltzmannian positrons. The properties of stationary structures are studied by pseudopotential approach, which is valid for large amplitude. It is found that the conditions which support the existence of solitons are alteredenActive galactic nucleiAstrophysical plasmaEarly universeElectron-positron plasmaIon acoustic solitonsLarge amplitudeNonthermal electronsNonthermal plasmaPseudopotential approachPulsar magnetosphereThree-componentOther