Surface metal abundances of red giants in galactic globular clusters

PARISI, M. C.; CLARIÁ, J. J.; TORRES, M. C.

San Juan - Argentina

Congreso; 47 Reunión de la Asociacón Argentina de Astronomía; 2004

Asociación Argentina de Astronomía

Surface metal abundances of 310 red giants in 19 Galactic globular clusters (GCs) are determined from the Standard Giant Branches method, using Washington photometric data. The resulting metallicities are compared with those derived by applying the traditional Colour-Colour (CC) technique. The low metallicities derived from the CC technique, particularly for some GCs, are found to be mainly due to the lower metallicity and higher reddening sensitivity of this method, especially for very metal-poor GCs ([Fe/H] < -1.7). The CC technique, however, is particularly recommendable to derive [Fe/H] values in the typical metallicity range of the galactic open clusters.