2004A&A...423..943T

We report Very Large Telescope (VLT) observations of the quasar PKS 2145+067. We obtained high-resolution (R≃100000 or 3km/s) optical spectra with the UV-Visual Echelle Spectrograph (UVES) at the VLT UT2 telescope. The emission redshift measured from [OIII] is z_em=1.0003. In our spectra, the well-known intervening metal-rich absorption system at z_abs=0.79089 shows MgII absorption lines resolved into 15 velocity components with a total spread of about 206km/s. This absorption is consistent with a line of sight passing through the extended gaseous halo of a disk galaxy. The derived Doppler line broadening parameters are in the range b=2 to 5km/s. We also detected absorption lines of MgI, FeII, and CaII in the same system. The ionization state of the absorbing gas is analyzed and compared with previous studies of PKS 2145+067. Finally, we discuss the implications of high-resolution data for proposed cosmological variations of the fine-structure constant.