ULTRA-HIGH-RESOLUTION OBSERVATIONS OF CA+ IONS IN THE LOCAL INTERSTELLAR-MEDIUM

We present ultra-high-resolution (0.3 km s(-1) FWHM) spectra of the interstellar Ca K line towards the nearby stars alpha Oph, alpha Gru and alpha Eri. These are the highest resolution absorption-line spectra yet obtained of clouds located within the local interstellar bubble. They have enabled us to resolve the line profiles fully, and reveal structure within components which have, until now, been considered as arising in single clouds. The velocity dispersions (b-values) of the identified components all have well-determined values in the range 1.4-2.3 km s(-1), consistent with thermal broadening at temperatures in the range 5000-13000 K.