We have performed a detailed spectral analysis of the inner halo Galactic globular cluster (GC) NGC 6723 using high-resolution (R ≈ 22 000-48 000) spectra for for 11 red giant branch stars collected with MIKE (Magellan) and FEROS (MPG/ESO). This globular is located at the minimum of the bimodal metallicity distribution of GCs, which suggests that it might be an excellent transitional system between metal-intermediate and metal-rich GCs. In spite of its metal-intermediate status, it is characterized by an extended horizontal branch and by a large number of RR Lyrae stars. We investigated abundances of a variety of species, including light, α-, Fe-peak, and neutron-capture elements. We found a mean metallicity [Fe/H]=-0.93 ± 0.05 dex and typical α-enrichment ([α Fe] ≈ 0.39) that follows the trend of metal-poor and metal-intermediate GCs. The same outcome applies for light metals (Na, Al), Fe-peak (V, Cr, Mn, Fe, Co, Ni, Cu) and s/r-process elements (Ba, Eu), and for the classical anticorrelation: Na-O and Mg-Al. The current findings further support the evidence that the chemical enrichment of NGC 6723 is more in line with metal-intermediate GCs and their lower metallicity counterparts, and it does not bring forward the prodrome of the metal-rich regime.
Chemical abundances in the metal-intermediate GC NGC 6723 / Crestani, J.; Alves-Brito, A.; Bono, G.; Puls, A. A.; Alonso-Garcia, J.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 487:4(2019), pp. 5463-5474. [10.1093/mnras/stz1674]
Chemical abundances in the metal-intermediate GC NGC 6723
Crestani J.Primo
;
2019
Abstract
We have performed a detailed spectral analysis of the inner halo Galactic globular cluster (GC) NGC 6723 using high-resolution (R ≈ 22 000-48 000) spectra for for 11 red giant branch stars collected with MIKE (Magellan) and FEROS (MPG/ESO). This globular is located at the minimum of the bimodal metallicity distribution of GCs, which suggests that it might be an excellent transitional system between metal-intermediate and metal-rich GCs. In spite of its metal-intermediate status, it is characterized by an extended horizontal branch and by a large number of RR Lyrae stars. We investigated abundances of a variety of species, including light, α-, Fe-peak, and neutron-capture elements. We found a mean metallicity [Fe/H]=-0.93 ± 0.05 dex and typical α-enrichment ([α Fe] ≈ 0.39) that follows the trend of metal-poor and metal-intermediate GCs. The same outcome applies for light metals (Na, Al), Fe-peak (V, Cr, Mn, Fe, Co, Ni, Cu) and s/r-process elements (Ba, Eu), and for the classical anticorrelation: Na-O and Mg-Al. The current findings further support the evidence that the chemical enrichment of NGC 6723 is more in line with metal-intermediate GCs and their lower metallicity counterparts, and it does not bring forward the prodrome of the metal-rich regime.File | Dimensione | Formato | |
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