NGC 6558
| dc.contributor.author | Barbuy, B. | |
| dc.contributor.author | Zoccali, M. | |
| dc.contributor.author | Ortolani, S. | |
| dc.contributor.author | Minniti, D. | |
| dc.contributor.author | Hill, V. | |
| dc.contributor.author | Renzini, A. | |
| dc.contributor.author | Bica, E. | |
| dc.contributor.author | Gomez, A. | |
| dc.date.accessioned | 2025-01-21T01:05:23Z | |
| dc.date.available | 2025-01-21T01:05:23Z | |
| dc.date.issued | 2007 | |
| dc.description.abstract | We present, for the first time, a detailed abundance analysis of five giant stars in the moderately metal-poor bulge globular cluster NGC 6558. Spectra have been obtained at the VLT with the multifiber spectrograph FLAMES in GIRAFFE mode ( R similar to 22; 000). The resulting iron abundance is [Fe/H] = -0. 97 +/- 0.15, in good agreement with the metallicity inferred from the slope of the red giant branch, but unusually high for a cluster with such a blue horizontal branch, possibly indicating an old age. A color-magnitude diagram in Vand I, based on photometry obtained with the Wide-Field Imager at ESO, is also presented. An isochrone of 14 Gyr fits the evolutionary sequences, confirming an old age. NGC 6558 is another "second-parameter'' bulge cluster. The metallicity derived is near the end of the low-metallicity tail of the bulge field-star distribution; hence, it presumably formed at the very early stages of the bulge formation. Abundance ratios show enhancements of the alpha-elements oxygen, magnesium, and silicon, with [O/Fe] = +0.38, [Mg/Fe] = +0.24, [Si/Fe] = +0.23, and solar calcium and titanium. The r-element europium is also enhanced by [Eu/Fe] = +0.36. The odd-Z elements sodium and aluminum, as well as the s-elements barium and lanthanum, show solar ratios. A heliocentric radial velocity of v(r)(hel) = -197.3 +/- 4 km s(-1) is found for NGC 6558. | |
| dc.fuente.origen | WOS | |
| dc.identifier.eissn | 1538-3881 | |
| dc.identifier.issn | 0004-6256 | |
| dc.identifier.uri | https://repositorio.uc.cl/handle/11534/95904 | |
| dc.identifier.wosid | WOS:000249781800029 | |
| dc.issue.numero | 4 | |
| dc.language.iso | en | |
| dc.pagina.final | 1625 | |
| dc.pagina.inicio | 1613 | |
| dc.revista | Astronomical journal | |
| dc.rights | acceso restringido | |
| dc.subject | globular clusters : general | |
| dc.subject | globular clusters : individual (NGC 6558) | |
| dc.title | NGC 6558 | |
| dc.type | artículo | |
| dc.volumen | 134 | |
| sipa.index | WOS | |
| sipa.trazabilidad | WOS;2025-01-12 |