J/A+AS/121/95 J/A+AS/121/95 Atmospheric parameters for 24 clusters E Carretta R G Gratton Astron. Astrophys. Suppl. Ser. 121 95 1997 1997A&AS..121...95C Abundances, [Fe/H] Effective temperatures globular clusters: general stars: abundances stars: Population II We have obtained high resolution, high signal-to-noise ratio CCD echelle spectra of 10 bright red giants in 3 globular clusters (47 Tuc, NGC 6752 and NGC 6397) roughly spanning the whole range of metallicities of the galactic globular cluster system. The analysis of this newly acquired material reveals no significant evidence of star-to-star variation of the [Fe/H] ratio in these three clusters. Moreover, a large set of high quality literature data (equivalent widths from high dispersion CCD spectra) was re-analyzed in an homogeneous and self-consistent way to integrate our observations and derive new metal abundances for more than 160 bright red giants in 24 globular clusters (i.e. about 16% of the known population of galactic globulars). This set was then used to define a new metallicity scale for globular clusters which is the result of high quality, direct spectroscopic data, of new and updated model atmospheres from the grid of Kurucz (1992), and of a careful fine abundance analysis; this last, in turn, is based on a common set of both atomic and atmospheric parameters for all the stars examined.

NGC NGC designation --- Name Star name --- Source Source for equivalent width --- Teff Effective Temperature (K) K logg Surface gravity cm/s2 [A/H] Abundance Sun Vel Microturbulent velocities km/s nFeI Number of FeI lines used --- logn(FeI) Absolute number density abundances of FeI --- e_logn(FeI) Sigma for Fe I abundances --- nFeII Number of FeII lines used --- logn(FeII) Absolute number density abundances of FeII --- e_logn(FeII) Sigma for Fe II abundances --- [Fe/H] Metallicity --- Patricia Bauer CDS 1996Jun03Eugenio Carretta <CARRETTA@astbo3.bo.astro.it> J_A+AS_121_95.xml