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| Paper: |
New Age and Abundance Estimates For NGC 6723: Clues Regarding Formation of the Inner Halo |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
265 |
| Authors: |
Fullton, L. K.; Carney, B. W. |
| Abstract: |
Ages of globular clusters in the inner halo provide strong constraints on viable Milky Way Formation scenarios. We present new age and abundance estimates for NGC 6723, chosen for study because of its proximity to the Galactic Center (RGC ~ 2.5 kpc), its similarity in metal abundance to the mean metallicity of bulge RR Lyraes ([Fe/H] = -1.1 dex) and because available kinematic information suggests that it is a long-term resident of the inner halo. High-resolution echelle spectra of member giants indicate that NGC 6723 is more metal-poor than previously thought ([Fe/H] = -1.26+/-0.09), in keeping with its very blue horizontal branch morphology. Measurements of [alpha /Fe] and [O/Fe] indicate that its elemental ratios are typical. Our BV CMD suggests that to within the measurement uncertainties, NGC 6723 is coeval with ``typical'' halo globular clusters of comparable metallicity that are farther from the Galactic Center. |
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