Bibcode
DOI
Forbes, Duncan A.; Beasley, Michael A.; Brodie, Jean P.; Kissler-Patig, Markus
Bibliographical reference
The Astrophysical Journal, Volume 563, Issue 2, pp. L143-L146.
Advertised on:
12
2001
Journal
Citations
63
Refereed citations
62
Description
We present high signal-to-noise Keck spectra for 10 globular clusters
associated with the giant Fornax elliptical galaxy NGC 1399 and compare
measured line indices with current stellar population models. Our data
convincingly demonstrate, for the first time, that at least some of the
clusters in a giant elliptical galaxy have supersolar abundance ratios,
similar to the host galaxy. From Hβ line strengths, the majority of
clusters have ages of ~11 Gyr (within 2σ), which is similar to the
luminosity-weighted stellar age of NGC 1399. Two of the clusters (which
also reveal enhanced abundance ratios) show significantly higher Hβ
values than the others. It remains unclear whether this is due to young
(~2 Gyr) ages or extremely old (>15 Gyr) ages with a warm blue
horizontal branch. However, a conflict with current cosmological
parameters is avoided if the young age is favored. Either alternative
indicates a complicated age distribution among the metal-rich clusters
and sets interesting constraints on their chemical enrichment at late
epochs.