Predicted and Empirical Radii of RR Lyrae Stars

M. Marconi, T. Nordgren, G. Bono, G. Schnider, F. Caputo
2005 Astrophysical Journal  
We present new theoretical Period-Radius-Metallicity (PRZ) relations for RR Lyrae stars. Current predictions are based on a large set of nonlinear, convective models that cover a broad range of chemical abundances and input parameters. We also provide new and homogeneous estimates of angular diameters for a sample of field RR Lyrae stars using a recent calibration of the Barnes-Evans surface brightness relation. Predicted and empirical radii are, within the errors, in reasonable agreement, but
more » ... n the short-period range the latter present a larger scatter. As a working hypothesis we suggest that this discrepancy might be due to the occurrence either of nonlinear features such as bumps or a steep rising branch. New distance determination for RR Lyr itself is in very good agreement with HST trigonometric parallax and with pulsation parallax.
doi:10.1086/430273 fatcat:4zjz333swvflber4i6wud22pky