Observational Studies of Cepheids. IV. The Feinheit Functions
Abstract
The properties of the Feinheit functions and their use in Cepheid distance determination are examined. Three Feinheit-type functions have been proposed: the W function of van den Bergh (1968, 1975), the Wesenheit function of Madore (1985) and the random-phase F function of Madore. The W function permits formation of a color-independent W-log P relation which is useful for distance determination and which is relatively insensitive to reddening. The Wesenheit function permits formation of a reddening free index for Cepheids, but not a color-independent Wesenheit-log P relation. Finally, the fundamental assumption of the random-phase Feinheit function F is shown to be false, leading to a nonlinear F-log P relation. The nature of the nonlinearity depends upon galactic properties which may differ from galaxy to galaxy. Distances obtained from the random-phase Feinheit function may be in error by several tenths of a magnitude as a result.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1986
- DOI:
- 10.1086/164196
- Bibcode:
- 1986ApJ...304..607M
- Keywords:
-
- Cepheid Variables;
- Distance;
- Functions (Mathematics);
- Galaxies;
- Stellar Oscillations;
- Stellar Spectrophotometry;
- Computational Astrophysics;
- Line Spectra;
- Astrophysics;
- GALAXIES: DISTANCES;
- PHOTOMETRY;
- STARS: CEPHEIDS;
- STARS: PULSATION