Portal de Periódicos da CAPES

Artigo Acesso aberto Produção Nacional Revisado por pares

BIBTEX RIS

HST NICMOS photometry of the reddened bulge globular clusters NGC 6528, Terzan 5, Liller 1, UKS 1 and Terzan 4

2001; EDP Sciences; Volume: 376; Issue: 3 Linguagem: Inglês

10.1051/0004-6361

1432-0746

S. Ortolani, B. Barbuy, E. Bica, A. Renzini, M. Zoccali, R. Michael Rich, S. Cassisi,

Astronomy and Astrophysical Research

We present results from NICMOS Hubble Space Telescope observations of the reddened bulge globular clusters NGC 6528, Terzan 5, Liller 1, UKS 1 and Terzan 4, obtained through the filters F110W (1.1 μm) and F160W (1.6 μm) (nearly equivalent to J and H). For the first time the turnoff region of Liller 1 and the main sequence of Terzan 5 and Terzan 4 are reached, as well as the horizontal branch of UKS 1. The magnitude difference between the turnoff and the red horizontal branch is used as an age indicator. From comparisons with new isochrones in the NICMOS photometric system, we conclude that the two metal-rich clusters NGC 6528 and Terzan 5 are coeval within uncertainties (~) with 47 Tucanae. Liller 1 and UKS 1 are confirmed as metal-rich globular clusters. Terzan 4 is confirmed as an interesting case of a metal-poor cluster in the bulge with a blue horizontal branch.