Ion-acoustic solitons in weakly relativistic plasma containing electron-positron and ion

The ion-acoustic solitons in a weakly relativistic electron-positron-ion plasma have been investigated. Such plasmas frequently occur in some astrophysical environment. We have used the reductive perturbation method (RPM) to study the characteristic of ion-acoustic solitary waves in this three component plasma. The KdV equation derived by RPM is solved and its solitonic behavior is studied as a function of number of parameters like densities of electron and positron, relative temperature ratio of electron to positron and relativistic factor. We have observed that these parameters significantly influence the peak amplitude and width of the solitons. Only compressive solitons are obtained. No double layers in the given parameter regime are possible.