An abundance analysis of the F-type giant HD116745 in the globular cluster Omega Centauri

Spectrograms obtained with a McGee spectracon image tube at a dispersion of 22.5 Å mm −1 have been used for a differential curve-of-growth analysis of the F giant HD 116745 ω Cen. The principal result of the analysis of one spectrum yields a logarithmic iron-to-hydrogen ratio with respect to the Sun of [Fe/H] = −1.2±0.3 (estimated error), as compared to a value ∼ −1.7 expected for cluster giants from ultra-violet excess and Deutsch/Kinman classification. A mass of 0.37 ℳ⊙|$^{+0.37}_{-0.18}\big \}$| is derived from the temperature, gravity and luminosity. A brief discussion of possible interpretations of these results is given.