The Distance to M5 from Its RR Lyrae Variables
Abstract
A variation of the Baade-Wesselink method has been applied to four RR Lyrae variables in the moderately metal-poor globular cluster M5. The method developed for the analysis utilizes an effective wavelength for each filter and relies on the accuracy of the calibration of absolute flux for bright standard stars by Oke and Gunn (1983), as well as on the accuracy of the absolute emitted fluxes predicted in the near-infrared by the Kurucz (1979) grid of model stellar atmospheres. The results must be viewed as preliminary thus far due to apparent discrepancies between the photometrically and spectroscopically deduced angular diameter-phase relationships which are most apparent in the part of the cycle immediately following maximum light. This restricts the range of phase that can be used to derive the distance to the variables. The best value obtained for the mean of the 4 RR Lyrae stars in M5 is an absorption-corrected intensity mean absolute V magnitude of +1.05 mag (+0.15, -0.25 mag).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1987
- DOI:
- 10.1086/165362
- Bibcode:
- 1987ApJ...318..215C
- Keywords:
-
- Astrometry;
- Computational Astrophysics;
- Globular Clusters;
- Variable Stars;
- Radial Velocity;
- Spectrum Analysis;
- Stellar Spectrophotometry;
- Astrophysics;
- CLUSTERS: GLOBULAR;
- STARS: RR LYRAE