  The aim of this research is to show that the processes of absorption
charge-exchange and photo-association in $A+B^{+}$ collisions together with the
processes of $AB^{+}$ photo-dissociation in the case of strongly non-symmetric
ion-atom systems, significantly influence the opacity of stellar atmospheres in
ultraviolet (UV) and extreme UV (EUV) region. In this work, the significance of
such processes for solar atmosphere is studied. In the case of the solar
atmosphere the absorption processes with $A=$ H and $B=$ Mg and Si are treated
as dominant ones, but the cases $A=$ H and $B=$ Al and $A=$ He and $B=$ H are
also taken into consideration. The choice of just these species is caused by
the fact that, of the species relevant for the used solar-atmosphere model, it
was only for them that we could determine the necessary characteristics of the
corresponding molecular ions, i.e. the molecular potential curves and dipole
matrix elements. It is shown that the efficiency of the examined non-symmetric
processes within the rather wide corresponding quasi-molecular absorption bands
in the far-UV and EUV regions is comparable and sometimes even greater than the
intensity of the known symmetric ion-atom absorption processes, which are
included now in the models of the solar atmosphere. Consequently, the presented
results suggest that the non-symmetric ion-atom absorption processes also have
to be included \emph{ab initio} in the corresponding models of the stellar
atmospheres.
