The Absolute Magnitudes of RR Lyrae Stars

Using firstly, the Hipparcos proper motions and the method of Statistical Parallax and secondly, the Hipparcos parallax of RR Lyrae itself and thirdly, the Baade-Wesselink results from the literature we find the zero-point of the RR Lyrae absolute magnitude - metallicity relation to be M v = 0.72\\Sigma0.10 at [Fe/H] = \\Gamma1:52. The small error on this zero-point reflects the remarkably good agreement between the three (independent) methods. Taking a value of 0.18\\Sigma0.03 for the slope of the relation from the literature we obtain a distance modulus of the LMC of 18.31. This is compared to other recent determinations of the distance to the LMC. 1. INTRODUCTION RR Lyraes are one of the primary distance indicators, both within the Galaxy and within the Local Group, and in this article we use the recently released Hipparcos data to estimate their absolute magnitudes. In Section 3 we consider the trigonometric parallaxes and in Section 4 the proper motions and the method of statistical ...