Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

The [Fe/H] Abundance Dispersion in the Remote Halo Globular Cluster NGC 5824 (#21)

Gary Da Costa 1
  1. Australian National University, Weston Creek, ACT, Australia

Star-to-star variations in light elements such as O and Na are ubiquitous within the Galaxy's globular cluster population.  However, there are relatively few clusters which show internal variations in the heavier elements such as Fe and Ca.  The stellar system omega Cen has long been known to possess a substantial internal abundance range, and more recently, smaller intrinsic [Fe/H] abundance dispersions have been established in other globular clusters such as M22 and M54.  In a recent paper (Saviane et al 2012, A&A, 504, A27) we suggested that the luminous (MV = -8.9) outer halo (Rgc = 26 kpc) globular cluster NGC5824 also possesses a small intrinsic [Fe/H] dispersion.  The result was based on spectra at the Ca triplet of 17 red giants.  Here I will present the results of an extensive follow-up spectroscopic study of red giants in the cluster based on Ca triplet spectroscopy obtained at the VLT with FORS2 and at Gemini-South with GMOS.  I will compare the resulting abundance distribution for NGC5824 with those for M22, M54 and omega Cen and comment on the possible connection between globular clusters like these and the disruption of dwarf galaxies during the formation of the Galaxy's halo.