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T. E. Nordgren, G. R. Schnider (U. of Redlands)
We calculate linear radii for a sample of 10 RR Lyrae stars. These radii are determined using a single Baade-Wesselink-type surface brightness relation calibrated from optical interferometric observations of evolved stars. We use these radii to generate period-radius diagrams for fundamental mode RR Lyrae stars. While logP-logR relations can be used to distinguish between various stellar models, our interest here is in making comparisons between various implementations (and calibrations) of the surface brightness relations used in the Baade-Wesselink method. We investigate the scatter in the logP-logR plane for linear radii calculated using photometry from the full range of pulsation phases versus those calculated where pulsation phase has been constrained to the range 0.0 to 0.8. We also investigate the scatter due to different calibrations of the surface brightness relation, such as using interferometric observations of Cepheids versus those using interferometric observations of non-pulsating giant stars. As a further check on all of these implementations, we compare the Baade-Wesselink distances calculated for the star RR Lyrae to the parallax distance calculated from direct Hubble Space Telescope Fine Guidance Sensor observations.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.