An Improved Metal Abundance Calibration for the Washington System
Abstract
The determination of metal abundances for individual giants from Washington photometry is revised, with several significant improvements incorporated. The solar-abundance two-color relations are revamped with the inclusion of new observations of a large sample of solar-abundance giants with small reddenings, especially those with late-K spectral types. The new relations are very similar to the original ones derived in C76 except for a zero-point offset. A new temperature index, M-T2, is investigated, as well as a new abundance index, C-T1, in addition to the standard indices. The M-T2 index has a much broader baseline and thus a much larger range than T1-T2, and is therefore less susceptible to photometric errors. The significant decrease in abundance sensitivity for cooler stars, suspected by previous investigations, is confirmed by including observations of a number of giants with a range in temperature in each of a large sample of open and globular clusters. A procedure for correcting the abundance indices for cool stars is derived which significantly improves the metallicity determination.
- Publication:
-
The Astronomical Journal
- Pub Date:
- November 1991
- DOI:
- 10.1086/116008
- Bibcode:
- 1991AJ....102.1836G
- Keywords:
-
- Abundance;
- Metallicity;
- Open Clusters;
- Stellar Spectrophotometry;
- Calibrating;
- G Stars;
- K Stars;
- Astronomy;
- INSTRUMENTS;
- STARS: ABUNDANCES