The self-enrichment of galactic halo globular clusters

Parmentier, G.; Gilmore, G.

doi:10.1051/0004-6361:20011173

Cited by 35 publications

(43 citation statements)

References 47 publications

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“…(1999), proto-GC clouds are confined by a hot protogalactic medium, and this model in fact predicts an inverse GC mass-metallicity relation, in which the most massive GCs are the most metal-poor (Parmentier & Gilmore 2001).…”

Section: The Blue Tiltmentioning

confidence: 97%

Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants and Dwarfs from Advanced Camera for Surveys Imaging

et al. 2006

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We have analyzed archival Hubble Space Telescope Advanced Camera for Surveys images in g and z of the globular cluster (GC ) systems of 53 ellipticals in the Virgo Cluster, spanning massive galaxies to dwarf ellipticals (dEs). Several new results emerged. (1) In the giant ellipticals (gEs) M87 and NGC 4649, there is a correlation between luminosity and color for individual blue (metal-poor) GCs, such that more massive GCs are more red (metal-rich). A plausible interpretation of this result is self-enrichment, and a speculative suggestion is that these GCs once possessed dark matter halos. (2) The dispersion in color is nearly twice as large for the metal-rich GCs as for the metal-poor GCs. However, there is evidence for a nonlinear relation between g À z and metallicity, and the dispersion in metallicity may be the same for both subpopulations. (3) Very luminous, intermediate-color GCs are common in gEs. These objects may be remnants of many stripped dwarfs, analogs of ! Cen in the Galaxy. (4) There is a continuity of GC system colors from gEs to some dEs; in particular, many dEs have metal-rich GC subpopulations. We also confirm the GC color-galaxy luminosity relations found previously for both metal-poor and metal-rich GC subpopulations. (5) There are large differences in GC specific frequency among dEs, independent of the presence of a nucleus and the fraction of metal-rich GCs. Over À15 < M B < À18 we find little correlation between specific frequency and M B . But we do find evidence for two separate S N classes of dEs: those with B-band S N $ 2 and those with populous GC systems that have S N ranging from $5 to 20 with median S N $ 10. Together, these points suggest multiple formation channels for dEs in the Virgo Cluster. (6) The peak of the GC luminosity function (GCLF) is the same for both gEs and dEs. This is contrary to expectations of dynamical friction on massive GCs, unless the primordial GCLF varies between gEs and dEs. Among gEs the GCLF turnover varies by a surprisingly small 0.05 mag, an encouraging result for its use as an accurate standard candle.

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Section: The Blue Tiltmentioning

confidence: 97%

Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants and Dwarfs from Advanced Camera for Surveys Imaging

et al. 2006

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“…This is true for any cluster system characterised by a stellar IMF that is invariant, and if the cluster age range is a limited fraction of the mean age of the cluster population. As regards the old GCs in the Galactic halo, the range spanned by their visual M/L ratio is limited (i.e., Pryor & Meylan 1993; see also Parmentier & Gilmore 2001, their fig. 1), and the scatter partly reflects variations in the dynamical evolution of individual GCs.…”

Section: Old Globular Clustersmentioning

confidence: 99%

The Long-term Survival Chances of Young Massive Star Clusters

Grijs

Parmentier

2007

Chin. J. Astron. Astrophys.

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We review the long-term survival chances of young massive star clusters (YMCs), hallmarks of intense starburst episodes often associated with violent galaxy interactions. We address the key question as to whether at least some of these YMCs can be considered protoglobular clusters (GCs), in which case these would be expected to evolve into counterparts of the ubiquitous old GCs believed to be among the oldest galactic building blocks. In the absence of significant external perturbations, the key factor determining a cluster's long-term survival chances is the shape of its stellar initial mass function (IMF). It is, however, not straightforward to assess the IMF shape in unresolved extragalactic YMCs. We discuss in detail the promise of using high-resolution spectroscopy to make progress towards this goal, as well as the numerous pitfalls associated with this approach. We also discuss the latest progress in worldwide efforts to better understand the evolution of entire cluster systems, the disruption processes they are affected by, and whether we can use recently gained insights to determine the nature of at least some of the YMCs observed in extragalactic starbursts as proto-GCs. We conclude that there is an increasing body of evidence that GC formation appears to be continuing until today; their long-term evolution crucially depends on their environmental conditions, however.

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“…8, which shows a small trend of [Ca/Fe] with metallicity. Indeed, Parmentier & Gilmore (2001), who studied the chemical enrichment of PGCCs with varying initial mass, predict that, the more massive the PGCCs, the lower the [Fe/H] achieved. Our modified EASE scenario, in which the most massive PGCCs would produce the highest [α/Fe] and the lowest [Fe/H], could therefore explain the small trend with metallicity which is observed in Fig.…”

Section: Modified Ease Scenariomentioning

confidence: 99%

“…taken place in the GC where the stars were born, that is, the more efficient the accretion process, the larger the [Y/Fe] ratio. This EASE scenario (standing for Evaporation/ Accretion/Self-Enrichment), which was devised to interpret the observed abundance correlations, subsequently proved to be able to explain the observed metallicities of present-day Galactic halo GCs (Parmentier et al 1999) as well as the distance-metallicity relation for the subgroup of Galactic GCs belonging to the Old Halo (Parmentier et al 2000) and the mass-metallicity relation found for the same subgroup (Parmentier & Gilmore 2001).…”

Section: Introductionmentioning

confidence: 99%

Abundance correlations in mildly metal-poor stars

Decauwer

Jehin

Parmentier

et al. 2005

A&A

Self Cite

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Abstract. Accurate relative abundances have been obtained for carbon, oxygen, sodium, aluminium, silicon, and calcium in a sample of mildly metal-poor stars. This analysis complements a previous study carried out by Jehin et al. (1999, A&A, 341, 241), which provided the basis for the EASE scenario. This scenario postulates that field metal-poor stars were born in selfenriched proto-globular cluster clouds. By further investigating the correlations between the different α-element abundances, we propose a modified scenario for the formation of intermediate metallicity stars, in which the stars exhibiting lower than average α/Fe abundance ratios would form in low mass clouds, unable to sustain the formation of very massive stars (M > ∼ 30 M ). Moreover, the carbon-to-iron ratio is found to decrease as one climbs the so-called Population IIb branch, i.e. when the s-element abundance increases. In the framework of the EASE scenario, we interpret this anticorrelation between the carbon and the s-element abundances as a signature of a hot bottom burning process in the metal-poor AGB stars which expelled the matter subsequently accreted by our Population IIb stars.

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The self-enrichment of galactic halo globular clusters

Cited by 35 publications

References 47 publications

Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants and Dwarfs from Advanced Camera for Surveys Imaging

Globular Clusters in Virgo Ellipticals: Unexpected Results for Giants and Dwarfs from Advanced Camera for Surveys Imaging

The Long-term Survival Chances of Young Massive Star Clusters

Abundance correlations in mildly metal-poor stars

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