Spectral properties of backscattered solar Ly-α radiation in the heliosphere: A search for heliospheric boundary effects Original Research Article

We explore the imprints of the solar wind interaction with the local interstellar medium on spectral properties of backscattered solar Ly-α radiation. We employ a newly developed effective model for the interstellar H atom velocity distribution function in the heliosphere (). The model takes into account both global effects of H atom perturbations at the heliospheric boundaries and local (i.e. within 10–20 AU from the Sun) effects of the solar ionization, charge exchange, solar gravitation and radiation pressure. Backscattered solar Ly-α profiles, intensities, line-shifts and line-widths were computed at 1 AU for the anti-solar lines-of-sight. Then the intensities, line-shifts and line-widths are compared with those calculated by using more simplified one-component and two-component hot models. The largest differences between the new model and hot models are seen in the line-width of the backscattered Ly-α profiles. The line-width is very sensitive to the kinetic properties of the H atom distribution function after passing the interaction region between the solar wind and the interstellar medium.