Journal
ASTRONOMY & ASTROPHYSICS
Volume 544, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201219897
Keywords
galaxies: individual: Fornax dSph; galaxies: star clusters: general; galaxies: stellar content
Categories
Funding
- NWO/VIDI
- NSF [AST-1109878]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1109878] Funding Source: National Science Foundation
Ask authors/readers for more resources
Recently, high-dispersion spectroscopy has demonstrated conclusively that four of the five globular clusters (GCs) in the Fornax dwarf spheroidal galaxy are very metal-poor with [Fe/H] < -2. The remaining cluster, Fornax 4, has [Fe/H] = -1.4. This is in stark contrast to the field star metallicity distribution which shows a broad peak around [Fe/H] approximate to -1 with only a few percent of the stars having [Fe/H] < -2. If we only consider stars and clusters with [Fe/H] < -2 we thus find an extremely high GC specific frequency, S-N approximate to 400, implying by far the highest ratio of GCs to field stars known anywhere. We estimate that about 1/5-1/4 of all stars in the Fornax dSph with [Fe/H] < -2 belong to the four most metal-poor GCs. These GCs could, therefore, at most have been a factor of 4-5 more massive initially. Yet, the Fornax GCs appear to share the same anomalous chemical abundance patterns known from Milky Way GCs, commonly attributed to the presence of multiple stellar generations within the clusters. The extreme ratio of metal-poor GC-versus field stars in the Fornax dSph is difficult to reconcile with scenarios for self-enrichment and early evolution of GCs in which a large fraction (90%-95%) of the first-generation stars have been lost. It also suggests that the GCs may not have formed as part of a larger population of now disrupted clusters with an initial power-law mass distribution. The Fornax dSph may be a rosetta stone for constraining theories of the formation, self-enrichment and early dynamical evolution of star clusters.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available