The Local Interstellar Medium: Comparison with Ibex Results, Sightlines to Exoplanet Host Stars, and Trajectories of the Voyager Spacecraft
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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We report on our recent studies of the local interstellar medium LISM using high-resolution ultraviolet spectra of nearby stars with the Space Telescope Imaging Spectrograph STIS instrument on the Hubble Space Telescope HST. Our objective is to measure the physical properties, kinematics, and morphology of the LISM near the Sun. After describing our techniques, we call attention to the different direction and speed of the gas in the Local Interstellar Cloud LIC surrounding the Sun compared to the infall vector of neutral helium entering the heliosphere as measured by the Interstellar Boundary Explorer IBEX and Ulysses spacecraft. We then suggest possible explanations for the differences. We describe the cloud structure and gas properties along the lines of sight to 3 nearby exoplanet host stars. Finally, we determine the cloud structure and properties of the interstellar gas in the directions that the Voyager spacecraft are heading. In the trajectory of Voyager 2, there is no absorption from the LIC or the very close G cloud suggesting that the Sun may lie very close to the outer edge of the LIC or perhaps even outside of the LIC.