The Carina Project

摘要: We have performed a new abundance analysis of Carina Red Giant (RG) stars from spectroscopic data collected with UVES (high resolution) and FLAMES/GIRAFFE medium at ESO/VLT. The former sample includes 44 RGs, while the latter consists 65 (high) ~800 (medium covering significant fraction galaxy's RG branch (RGB), red clump stars. To improve faint magnitude limit, were divided into ten surface gravity effective temperature bins. spectra belonging to same gravity/temperature bin stacked. This approach allowed us increase by least factor five signal-to-noise ratio in limit (V>20.5mag). took advantage photometry index cU,B,I introduced Monelli et al. (2014), as an age probably metallicity indicator, split along RGB. These two stellar populations display distinct [Fe/H] [Mg/H] distributions: their mean Fe abundances are -2.15$\pm$0.06dex (sig=0.28), -1.75$\pm$0.03dex (sig=0.21), respectively. iron distributions differ 75% level. supports preliminary results Lemasle (2012) (2014). Moreover, we found that old intermediate-age -1.91$\pm$0.05dex (sig=0.22) -1.35$\pm$0.03dex (sig=0.22); these 83% Carina's {\alpha}-element agree, within 1sigma, similar for field Halo cluster (Galactic, Magellanic) outcome applies nearby dwarf spheroidals ultra-faint galaxies, range covered Finally, evidence clear correlation between Na O abundances, thus suggesting chemical enrichment history is quite different than globular clusters.