Ultrahigh resolution spectroscopy of a nearby high-latitude filament

We report new observations of Na I and Ca II interstellar absorption in a n earby (230 +/- 30 pc) southern high-latitude filament obtained at a spectro scopic resolution of similar to 0.32 km s(-1) using HD 22252 as the backgro und probe. Complex absorption is present for both species with total column densities of N(Ca II)similar to 1.3 x 10(12) cm(-2) and N(Na I) > 7 x 10(1 2) cm(-2). Over a velocity range of 25 km s(-1) we find 11 Ca II velocity c omponents loosely grouped into three velocity aggregates. Unusually narrow Ca II absorption is present with b-values in the range 0.25-0.5 km s(-1); s uch small values are rarely discovered. Each of these narrow Ca II componen ts has an associated broader component at a slightly shifted velocity. Fina lly, there are two Ca II clouds with large b-values (similar to 5 km s(-1)) but no detectable Na I that flank the three aggregates. At our particular intercept we may be observing the filament edge-on and seeing cold interior condensations each with a warm outer shell-all contained within a further exterior envelope of ionized gas. We estimate that a typical interior conde nsation will have a linear dimension d in the range 10(4) < d < 6 x 10(4) A U and a pressure nT of 1.5 < nT < 9 x 104 cm(-3) K, but with large uncertai nties. This result is consistent with the picture of small and relatively d ense cloud cores expanding into the local bubble.