Authors: F. Fraternale (University of Alabama in Huntsville - CSPAR), R. K. Bera (University of Alabama in Huntsville - CSPAR, USA), N. V. Pogorelov (University of Alabama in Huntsville - CSPAR, USA), J. Heerikhuisen (University of Waikato, NZ)

We present a new version of our recent 3-D MHD-plasma/Kinetic-neutral heliosphere model which includes self-consistently neutral hydrogen and helium atoms and their feedback on the plasma mixture and He⁺ ions from H+H⁺ and He+He⁺ charge-exchange collisions and photoionization. The new model treats electrons as a separate fluid, assumed to co-move with the plasma mixture. In addition, we include the effect of Coulomb collisions between electrons, He⁺ ions and protons. Treating electrons separately is meaningful because suprathermal electrons are not produced in the charge-exchange process, and the electron pressure may be overestimated when they are assumed to have the temperature of the ion mixture. On the other hand, the electron properties in the outer heliosphere are mostly unknown, and this model allows us to investigate the effects of different levels of thermalization of electrons on the filtration of interstellar neutrals and on the shape of the heliosphere. Using recent consensus values of the LISM properties, it is shown that the new model better reproduces the proton properties measured by New Horizons. An interesting result is that the modification of the charge-exchange rate due to cooler electrons in the inner heliosheath makes the heliosheath thinner by ~6% along the V1 direction. Our new simulations also confirm the previous results of our group concerning the comet-like shape of the heliosphere. Coulomb collisions are found to equilibrate the VLISM plasma components (assumed Maxwellian). The VLISM proton temperature near the heliopause ranges from 30,000 to 40,000 K, in agreement with recent Voyager 2/PLS observations.