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Paper: The absolute magnitude of RR Lyraes: from Hipparcos parallaxes and proper motions
Volume: 167, Harmonizing Cosmic Distance Scales in a Post-Hipparcos Era
Page: 316
Authors: Solano, E.; Barnes, T. G.
Abstract: We have used Hipparcos proper motions and the method of statistical parallaxes to estimate the absolute magnitude of RR Lyrae stars. In addition, we have used the Hipparcos parallax of RR Lyrae itself to determine its 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 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 methods. Potential problems that may affect the results are outlined.
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