HST Lyman-alpha absorption spectra toward nearby stars as a remote diagnostic of the heliosheath plasma properties

摘要

A self-consistent model of the solar wind interaction with the two-component (plasma and H atoms) interstellar medium is employed to calculate heliospheric Lyman-alpha absorption spectra. It is shown that the heliospheric absorption consists of absorption in the hydrogen wall region and in the heliosheath. Both absorption components are computed in different directions. We perform a parametric study by varying the proton and H atom number densities of the interstellar gas. The theoretical absorption spectra are compared with Hubble Space Telescope observations toward six nearby stars. Results of the comparison and possible constraints on the structure of the heliospheric interface are presented and discussed.