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| Paper: |
A Self-consistent, High Dispersion Metallicity Scale for Globular Clusters |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
363 |
| Authors: |
Carretta, E.; Gratton, R. G. |
| Abstract: |
A new metallicity scale is presented for galactic globular clusters (GGCs), completely based on direct, high-resolution spectroscopy of red giant stars in 21 clusters. High-resolution echelle spectra, newly acquired, are analyzed for a sample of giants in 47 Tuc, NGC 6752 and NGC 6397. Moreover, a large set of data from the literature is re-analyzed in an homogeneous way to integrate the observations and derive new metal abundances for 18 other clusters. The new metallicity scale is then the result of both high quality, direct spectroscopic data and the new, updated model atmospheres by Kurucz (1992); the internal mean error is 0.06 dex (21 clusters). The new [Fe/H] values are sistematically about 0.2 dex higher than those, widely used, by Zinn (1985), in the intermediate-metallicity regime; moreover, the Zinn's scale is shown to be not linear at both high and low metallicities, in comparison with our new scale. |
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