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The metallicity of the old open cluster NGC 6791

Raffaele Gratton·Angela Bragaglia·Eugenio Carretta·Monica Tosi
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Abstract

We have observed four red clump stars in the very old and metal-rich open cluster NGC 6791 to derive its metallicity, using the high resolution spectrograph SARG mounted on the TNG. Using a spectrum synthesis technique we obtain an average value of [Fe/H] = +0.47 (+/- 0.04, rms=0.08) dex. Our method was tested on mu Leo, a well studied metal-rich field giant. We also derive average oxygen and carbon abundances for NGC 6791 from synthesis of [O I] at 6300 A and C_2 at 5086 A, finding [O/Fe] =~ -0.3 and [C/Fe] =~ -0.2.

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Raffaele Gratton, Angela Bragaglia, Eugenio Carretta, Monica Tosi. 2006-01-02. The metallicity of the old open cluster NGC 6791. https://doi.org/10.1086/500729

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