SCYON Abstract

Received on February 10 2006

The metallicity of the old open cluster NGC 6791

AuthorsRaffaele Gratton (1), Angela Bragaglia (2), Eugenio Carretta (2), Monica Tosi (2)
(1) INAF-Osservatorio Astronomico di Padova
(2) INAF-Osservatorio Astronomico di Bologna
Accepted byAstrophysical Journal
Links NGC 6791


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 μ 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 C2 at 5086 A, finding [O/Fe]@-0.3 and [C/Fe]@-0.2.