The absolute magnitudes of RR Lyraes from HIPPARCOS parallaxes and proper motions

We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae stars. In addition we used the HIPPARCOS parallax of RR Lyrae itself to determine it's absolute magnitude. These two results are in excellent agreement with each other and give a zero-point for the RR Lyrae Mv,[Fe/H] relation of 0.77±0.15 at [Fe/H]=-1.53. This zero-point is in good agreement with that obtained recently by several groups using Baade-Wesselink methods which, averaged over the results from the different groups, gives Mv = 0.73±0.14 at [Fe/H]=-1.53. Taking the HIPPARCOS based zero-point and a value of 0.18±0.03 for the slope of the Mv,[Fe/H] relation from the literature we find firstly, the distance modulus of the LMC is 18.26±0.15 and secondly, the mean age of the Globular Clusters is 17.4±3.0 GYrs. These values are compared with recent estimates based on other 'standard candles' that have also been calibrated with HIPPARCOS data. It is clear that, in addition to astrophysical problems, there are also problems in the application of HIPPARCOS data that are not yet fully understood.