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I. Crawford, N. Craig (1), and B. Welsh
1) Center for EUV Astrophysics, 2150 Kittredge Street, University
of California, Berkeley, CA 94720
We present ultra-high-resolution (0.35 km/s FWHM) observations of the interstellar Ca K line towards eight nearby stars (six of which are closer than 30 pc). The spectral resolution is sufficient to resolve the line profiles fully, thereby enabling us to detect hitherto unresolved velocity components, and to obtain accurate measurements of the velocity dispersions (b-values). Absorption components due to the Local Interstellar Cloud (LIC) and/or the closely associated "G Cloud" are identified towards all but one star (gamma Oph), but only in one case (51 Oph) are both clouds reliably detected towards the same star. Most of these nearby clouds have velocity dispersions (b ~2 km/s) which suggest physical conditions similar to those inferred for the LIC (T_k ~7000 K, v_t ~1 km/s), although at least three lines of sight (towards gamma Aqr, beta Cen and rho Cen) also sample cooler and/or less turbulent material. The spectrum of the nearby Vega-excess star 51 Oph is of particular interest, owing to evidence that several of the absorption components arise in the circumstellar environment.
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