| Abstract: | We have used HIPPARCOS proper motions and the method of Statistical Parallax to estimate the absolute magnitude of RR Lyrae
stars. In addition, we have used the HIPPARCOS parallax of RR Lyr 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 assuming a value of 0.18 ± 0.03 for the slope
we find the distance modulus of the LMC is 18.26 ± 0.15. This value is compared with recent estimates based on other methods.
Potential problems that may affect the results are outlined.
This revised version was published online in July 2006 with corrections to the Cover Date. |
