Properties of the Interstellar Medium along Sight Lines to Nearby Planet
  Hosting Stars
  We analyze high-resolution ultraviolet spectra of three nearby exoplanet host
stars (HD 192310, HD 9826, and HD 206860) to study interstellar properties
along their lines of sight and to search for the presence of astrospheric
absorption. Using HST/STIS spectra of the Lyman-alpha, Mg II, and Fe II lines,
we identify three interstellar velocity components in the lines of sight to
each star. We can reliably assign eight of the nine components to partially
ionized clouds found by Redfield & Linsky (2008) on the basis of the star's
location in Galactic coordinates and agreement of measured radial velocities
with velocities predicted from the cloud velocity vectors. None of the stars
show blue-shifted absorption indicative of an astrosphere, implying that the
stars are in regions of ionized interstellar gas. Coupling astrospheric and
local interstellar medium measurements is necessary to evaluate the host star
electromagnetic and particle flux, which have profound impacts on the
atmospheres of their orbiting planets. We present a table of all known
exoplanets located within 20 pc of the Sun listing their interstellar
properties and velocities predicted from the local cloud velocity vectors.
