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Among the tens of thousands of known RR Lyrae stars there are only a handfulthat show indications of possible binarity. The question why this is the caseis still unsolved, and has recently sparked several studies dedicated to thesearch for additional RR Lyraes in binary systems. Such systems areparticularly valuable because they might allow to constrain the stellar mass.Most of the recent studies, however, are based on photometry by finding a lighttime effect in the timings of maximum light. This approach is a very promisingand successful one, but it has a major drawback: by itself, it cannot serve asa definite proof of binarity, because other phenomena such as the Blazhkoeffect or intrinsic period changes could lead to similar results. Spectroscopicradial velocity measurements, on the other hand, can serve as definite proof ofbinarity. We have therefore started a project to study spectroscopically RRLyrae stars that are suspected to be binaries. We have obtained radial velocity(RV) curves with the 2.1m telescope at McDonald observatory. From these wederive systemic RVs which we will compare to previous measurements in order tofind changes induced by orbital motions. We also construct templates of the RVcurves that can facilitate future studies. We also observed the most promisingRR Lyrae binary candidate, TU UMa, as no recent spectroscopic measurements wereavailable. We present a densely covered pulsational RV curve, which will beused to test the predictions of the orbit models that are based on the O-Cvariations.

New systemic radial velocities of suspected RR Lyrae binary stars