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Description
We present high-resolution spectroscopic observations and species-by-species radial velocities of a number of southern Cepheids. The stars (BP Cir, V350 Sgr, AX Cir, V636 Sco, W Sgr, S Mus, {beta} Dor, TT Aql, Y Oph, YZ Car, SW Vel, X Pup, T Mon and l Car) were observed as part of a long-term programme at Mt John University Observatory. Radial velocities were determined with the line bisector technique, and have a precision of ~300m/s. Velocity differences as large as 30km/s were found for H and Ca II when referenced to the metallic line velocity curves, but more subtle variations (of 12km/s) were also detected in many other species. Pulsational phase anticorrelations are found between lines of Si II and Ba II, confirming the propagation time delay between line-forming layers producing these two species. We find that the amplitude and phase differences between the various species increase with period.
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