New 3-D gas density maps of NaI and CaII interstellar absorption within
  300pc
  We present new high resolution (R>50,000) absorption measurements of the NaI
doublet (5889 - 5895A) along 482 nearby sight-lines, in addition to 807 new
measurements of the CaII K (3933A) absorption line. We have combined these new
data with previously reported measurements to produce a catalog of absorptions
towards a total of 1857 early-type stars located within 800pc of the Sun. Using
these data we have determined the approximate 3-dimensional spatial
distribution of neutral and partly ionized interstellar gasdensity within a
distance-cube of 300pc from the Sun. All newly recorded spectra were analyzed
by means of a multi-component line profile-fitting program, in most cases using
simultaneous fits to the line doublets. Normalized absorption profiles were
fitted by varying the velocity, doppler width and column density for all
intervening interstellar clouds. The resulting total column densities were then
used in conjunction with the Hipparcos distances of the target stars to
construct inversion maps of the 3-D spatial density distribution of the NaI and
CaII bearing gas. A plot of the equivalent width of NaI versus distance reveals
a wall of neutral gas at ~80pc that can be associated with the boundary wall to
the central rarefied Local Cavity region. In contrast, a similar plot for the
equivalent width of CaII shows no sharply increasing absorption at 80pc, but
instead we observe a slowly increasing value of CaII equivalent width with
increasing sight-line distance sampled.
