Observations towards early-type stars in the ESO-POP Survey - II. Searches for intermediate- and high-velocity clouds
We present Ca II K and Ti II optical spectra of early-type stars taken mainly from the ultraviolet and visual echelle spectrograph (UVES) Paranal Observatory Project, plus H I 21-cm spectra, from the Vila-Elisa and Leiden-Dwingeloo Surveys, which are employed to obtain distances to intermediate- and high-velocity clouds (IHVCs). H I emission at a velocity of -117 km s-1 towards the sightline HD 30677 ([ image ]) with column density ~1.7 × 1019 cm-2 has no corresponding Ca II K absorption in the UVES spectrum, which has a signal-to-noise ratio (S/N) of 610 per resolution element. The star has a spectroscopically determined distance of 2.7 kpc, and hence sets this as a firm lower distance limit towards Anti-Centre cloud ACII. Towards another sightline (HD 46185 with [ image ]), H I at a velocity of +122 km s-1 and column density of 1.2 × 1019 cm-2 is seen. The corresponding Ca II K spectrum has a S/N of 780, although no absorption is observed at the cloud velocity. This similarly places a firm lower distance limit of 2.9 kpc towards this parcel of gas that may be an intermediate-velocity (IV) cloud. The lack of IV Ca II absorption towards HD 196426 ([ image ]) at a S/N of 500 reinforces a lower distance limit of ~700 pc towards this part of complex gp, where the H I column density is 1.1 × 1019 cm-2 and velocity is +78 km s-1. Additionally, no IV Ca II is seen in absorption in the spectrum of HD 19445, which is strong in H I with a column density of 8 × 1019 cm-2 at a velocity of ~-42 km s-1, placing a firm although uninteresting lower distance limit of 39 pc to this part of IV South. Finally, no high-velocity Ca II K absorption is seen towards HD 115363 ([ image ]) at a S/N of 410, placing a lower distance of ~3.2 kpc towards the HVC gas at velocity of ~+224 km s-1 and H I column density of 5.2 × 1019 cm-2. This gas is in the same region of the sky as complex WE (Wakker 2001), but at higher velocities. The non-detection of Ca II K absorption sets a lower distance of ~3.2 kpc towards the HVC, which is unsurprising if this feature is indeed related to the Magellanic System.