RR Lyrae and Type II Cepheid Variables Adhere to a Common Distance\n Relation

Preliminary evidence is presented reaffirming that SX Phe, RR Lyrae, and Type\nII Cepheid variables may be characterized by a common Wesenheit\nperiod-magnitude relation, to first order. Reliable distance estimates to RR\nLyrae variables and Type II Cepheids are ascertained from a single VI-based\nreddening-free relation derived recently from OGLE photometry of LMC Type II\nCepheids. Distances are computed to RR Lyrae (d~260 pc), and variables of its\nclass in the galaxies IC 1613, M33, Fornax dSph, LMC, SMC, and the globular\nclusters M3, M15, M54, omega Cen, NGC 6441, and M92. The results are consistent\nwith literature estimates, and in the particular cases of the SMC, M33, and IC\n1613, the distances agree with that inferred from classical Cepheids to within\nthe uncertainties: no corrections were applied to account for differences in\nmetallicity. Moreover, no significant correlation was observed between the\ndistances computed to RR Lyrae variables in omega Cen and their metallicity,\ndespite a considerable spread in abundance across the sample. In sum, concerns\nregarding a sizeable metallicity effect are allayed when employing VI-based\nreddening-free Cepheid and RR Lyrae relations.\n