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High-resolution spectroscopic observations have been made of a number of southern Cepheids. The stars studied were part of a long-term programme to observe southern variable stars and to complete a data base of radial velocities over a long time interval. The radial velocities have a precision of 300 m s -1 , allowing the detection of velocity differences of 1 km s -1 with confidence. Our new data provide a consistent set of data against which other sources of data can be compared.
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Petterson et al. (2004) studied this question.
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