  Due to its inclined orbit and the complex geometry of the magnetic field of
Neptune, Triton experiences a highly variable magnetic environment. As
precipitation of magnetospheric electrons is thought to have a large impact on
the Triton atmosphere, a better understanding of the interaction between its
atmosphere and the magnetosphere of Neptune is important. We aim to couple a
model of the Triton atmosphere with an electron transport model to compute the
impact of a varying electron precipitation on the atmospheric composition. We
coupled a recent photochemical model of the Triton atmosphere with the electron
transport model TRANSPlanets. The inputs of this code were determined from
Voyager 2 observations and previous studies. The main inputs were the electron
precipitation flux, the orbital scaling factor, and the magnetic field
strength. The electron-impact ionization and electron-impact dissociation rates
computed by TRANSPlanets were then used in the photochemical model. We also
analyzed the model uncertainties. The coupling of the two models enabled us to
find an electron density profile, as well as N$_2$ and N number densities, that
are consistent with the Voyager 2 observations. We found that photoionization
and electron-impact ionization are of the same order, in contrast to the
results of previous photochemical models. However, we emphasize that this
result depends on the hypotheses we used to determine the input variables of
TRANSPlanets. Our model would greatly benefit from new measurements of the
magnetic environment of Triton, as well as of the electron fluxes in the
Neptune magnetosphere.
