The Baade-Wesselink Method and the Distances to RR Lyrae Stars. IV. The Flux Distribution of RR Lyrae Variables
Abstract
Corrections are applied to the synthetic J - K and Cousins V - I color indices derived from the unpublished models of Kurucz in order to obtain agreement with the observed colors of dwarfs of known metallicity. These corrected colors are used to extend the analysis of the moderately metal-rich field RR Lyrae star SW Draconis by applying the surface brightness version of the Baade-Wesselink method to the K, J - K and Ic, V - Ic magnitude-color combinations. It is discovered that the K, J - K combination can yield good results if the J - K values can be accurately measured. The distribution of flux with respect to wavelength of both SW Dra and the very metal poor variable X Arietis is derived throughout the pulsation cycle and the results compared to those of static stars in an attempt to discover the cause of the discrepancy during the expansion phase between the temperatures derived from optical color indices and the temperature obtained from V - K. This discrepancy results from an excess of flux in the B filter and a deficiency in flux in the Rc and Ic filters in this phase region compared to that of the K filter, perhaps due to either a change in the opacity structure of the atmosphere caused by the strong acceleration during the phase of maximum V light or emission generated by shock waves or both. Preliminary observations of the intermediate metallicity variable RR Ceti are reported, and it is determined that the temperature discrepancy during the expansion phase also occurs for this star. There are too few observations to derive an accurate value of <Mv> for this star.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1988
- DOI:
- 10.1086/166092
- Bibcode:
- 1988ApJ...326..305J
- Keywords:
-
- Distance;
- Stellar Luminosity;
- Stellar Oscillations;
- Stellar Spectrophotometry;
- Variable Stars;
- Metallicity;
- Stellar Color;
- Stellar Magnitude;
- Astrophysics;
- SPECTROPHOTOMETRY;
- STARS: INDIVIDUAL CONSTELLATION NAME: SW DRACONIS;
- STARS: INDIVIDUAL CONSTELLATION NAME: RR CETI;
- STARS: LUMINOSITIES;
- STARS: PULSATION;
- STARS: RR LYRAE