Hydrogen wall and heliosheath Ly α absorption toward nearby stars: Possible constraints on the heliospheric interface plasma flow

[1] In this paper, we study heliospheric Ly α absorption toward nearby stars in different lines of sight. We use the Baranov–Malama model of the solar wind interaction with a two-component (charged component and H atoms) interstellar medium. Interstellar atoms are described kinetically in the model. The code allows us to separate the heliospheric absorption into two components, produced by H atoms originating in the hydrogen wall and heliosheath regions, respectively. We study the sensitivity of the heliospheric absorption to the assumed interstellar proton and H atom number densities. These theoretical results are compared with interstellar absorption toward six nearby stars observed by the Hubble Space Telescope (HST).