A NEW DETERMINATION OF THE LOCAL-DISTRIBUTION OF INTERSTELLAR NA-I

We present galactic maps of the distribution of neutral sodium absorpt ion column density using the newly determined Hipparcos satellite dist ances for a total of 290 stars lying within 250 pc of the Sun. These m aps now replace those originally presented in Welsh et al. (1994). The Local Bubble is now seen to be a neutral gas-free cavity (n(H) < 0.01 cm(-3)) with a radius of at least 70pc in most directions, more than 50% larger in volume than previously determined from Na I absorption d ata. Additionally, the well-known low-density interstellar tunnel in t he direction of the star beta CMa is almost twice as wide as previousl y thought, and the existence of a similarly tenuous interstellar featu re has been identified in the galactic direction of Lupus-Norma extend ing to at least 170 pc. Finally, we note the absence of dense neutral gas out to a distance of at least 100 pc in the direction of galactic longitude l(II) = 135 degrees.