Helium-rich white dwarf atmospheres: the non-symmetric ion-atom absorption processes

Abstract

Here, the processes of photo-association and absorption charge-exchange in He+H+ collisions together with the process of molecular ion HeH+ photo-dissociation are considered as factors of influence on the opacity of the atmospheres of helium-rich white dwarfs in the far UV region. It is shown that they should be taken into account even in the cases of the atmospheres of white dwarfs with H:He =10−5. Also, it is established that in the cases of white dwarfs with H:He ≳ 10−4, especially when H:He ≈ 10−3, these processes have to be included ab initio in the corresponding models of their atmospheres.