Physical and chemical characteristics of the ISM inside and outside the heliosphere

Abstract : This paper summarizes some of the discussions of working group 8–9 during the ISSI Conference on “The Heliosphere in the Local Interstellar Medium”. Because the subject of these working groups has become significantly broader during the last ten years, we have selected three topics for which recent observations have modified and improved our knowledge of the heliosphere and the surrounding interstellar medium. These topics are the number densities and ISM ionization states of hydrogen and helium, the newly discovered hot gas from the “H wall” seen in absorption, and the comparison between ISM and heliospheric minor element abundances. Papers from this volume in which more details on these topics can be found are quoted throughout the report.