High resolution spectroscopic analysis of seven giants in the bulge globular cluster NGC 6723

Abstract

Globular clusters associated with the Galactic bulge are important tracers of stellar populations in the inner Galaxy. High resolution analysis of stars in these clusters allows us to characterize them in terms of kinematics, metallicity, and individual abundances, and to compare these fingerprints with those characterizing field populations. We present iron and element ratios for seven red giant stars in the globular cluster NGC~6723, based on high resolution spectroscopy. High resolution spectra ($R\sim 48000$) of seven K giants belonging to NGC 6723 were obtained with the FEROS spectrograph at the MPG/ESO 2.2m telescope. Photospheric parameters were derived from $\sim 130$ FeI and FeII transitions. Abundance ratios were obtained from line-to-line spectrum synthesis calculations on clean selected features. An intermediate metallicity of [Fe/H]$=-0.98\pm 0.08$ dex and a heliocentric radial velocity of $v_{hel}=-96.6\pm 1.3km{s}^{-1}$ were found for NGC 6723. Alpha-element abundances present enhancements of $[O/Fe]=0.29\pm 0.18$ dex, $[Mg/Fe]=0.23\pm 0.10$ dex, $[Si/Fe]=0.36\pm 0.05$ dex, and $[Ca/Fe]=0.30\pm 0.07$ dex. Similar overabundance is found for the iron-peak Ti with $[Ti/Fe]=0.24\pm 0.09$ dex. Odd-Z elements Na and Al present abundances of $[Na/Fe]=0.00\pm 0.21$ dex and $[Al/Fe]=0.31\pm 0.21$ dex, respectively. Finally, the s-element Ba is also enhanced by $[Ba/Fe]=0.22\pm 0.21$ dex. The enhancement levels of NGC 6723 are comparable to those of other metal-intermediate bulge globular clusters. In turn, these enhancement levels are compatible with the abundance profiles displayed by bulge field stars at that metallicity. This hints at a possible similar chemical evolution with globular clusters and the metal-poor of the bulge going through an early prompt chemical enrichment.

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Cited by in corpus (12)

• N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes
• APOGEE discovery of a chemically atypical star disrupted from NGC 6723 and captured by the Milky Way bulge
• Exploring the Chemical Composition and Double Horizontal Branch of the Bulge Globular Cluster NGC 6569
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XX. Ages of single and multiple stellar populations in seven bulge globular clusters
• Chemical Study of the Metal-rich Globular Cluster NGC 5927
• From globular clusters to the disc: the dual life of our Galaxy
• Reversed radial distribution trend of subpopulations in the globular clusters NGC 362 and NGC 6723
• Chemical abundances in the metal-intermediate GC NGC 6723
• Isochrone fitting of Galactic globular clusters -- IV. NGC6362 and NGC6723
• Globular Clusters Lost by the Sagittarius Dwarf Spheroidal Galaxy
• Integrated Spectra of Milky Way Globular Cluster
• Carbon Abundance Inhomogeneities and Deep Mixing Rates in Galactic Globular Clusters