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Primordial r-process Dispersion in Metal-Poor Globular Clusters
Astrophysics of Galaxies · Submitted 27 Apr 2011
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution.
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Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). Recent detections of low [Pb/Eu] ratios or upper limits in several metal-poor GCs indicate that the heavy elements in these GCs were produced exclusively by an r-process. Reexamining GC heavy element abundances from the literature, we find unmistakable correlations between the [La/Fe] and [Eu/Fe] ratios in 4 metal-poor GCs (M5, M15, M92, and NGC 3201), only 2 of which were known previously. This indicates that the total r-process abundances vary star-to-star (by factors of 2-6) relative to Fe within each GC. We also identify potential dispersion in two other GCs (M3 and M13). Several GCs (M12, M80, and NGC 6752) show no evidence of r-process dispersion. The r-process dispersion is not correlated with the well-known light element dispersion, indicating it was present in the gas throughout the duration of star formation. The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). | background 0.99 | 0.04 | 0.03 | asserted 1.00 |
| s1 | Recent detections of low [Pb/Eu] ratios or upper limits in several metal-poor GCs indicate that the heavy elements in these GCs were produced exclusively by an r-process. | background 0.93 | 0.06 | 0.04 | hedged possibility 0.68 |
| s2 | Reexamining GC heavy element abundances from the literature, we find unmistakable correlations between the [La/Fe] and [Eu/Fe] ratios in 4 metal-poor GCs (M5, M15, M92, and NGC 3201), only 2 of which were known previously. | result 0.91 | 0.95 | 0.16 | asserted 1.00 |
| s3 | This indicates that the total r-process abundances vary star-to-star (by factors of 2-6) relative to Fe within each GC. | result 0.64 | 0.91 | 0.27 | hedged possibility 0.56 |
| s4 | We also identify potential dispersion in two other GCs (M3 and M13). | result 1.00 | 0.90 | 0.04 | hedged possibility 0.97 |
| s5 | Several GCs (M12, M80, and NGC 6752) show no evidence of r-process dispersion. | result 1.00 | 0.65 | 0.04 | asserted 0.99 |
| s6 | The r-process dispersion is not correlated with the well-known light element dispersion, indicating it was present in the gas throughout the duration of star formation. | interpretation 0.63 | 0.78 | 0.09 | asserted 0.99 |
| s7 | The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution. | interpretation 0.99 | 0.39 | 0.90 | hedged possibility 1.00 |
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Original abstract
Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). Recent detections of low [Pb/Eu] ratios or upper limits in several metal-poor GCs indicate that the heavy elements in these GCs were produced exclusively by an r-process. Reexamining GC heavy element abundances from the literature, we find unmistakable correlations between the [La/Fe] and [Eu/Fe] ratios in 4 metal-poor GCs (M5, M15, M92, and NGC 3201), only 2 of which were known previously. This indicates that the total r-process abundances vary star-to-star (by factors of 2-6) relative to Fe within each GC. We also identify potential dispersion in two other GCs (M3 and M13). Several GCs (M12, M80, and NGC 6752) show no evidence of r-process dispersion. The r-process dispersion is not correlated with the well-known light element dispersion, indicating it was present in the gas throughout the duration of star formation. The observations available at present suggest that star-to-star r-process dispersion within metal-poor GCs may be a common but not ubiquitous phenomenon that is neither predicted by nor accounted for in current models of GC formation and evolution.
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What this paper does with the arXiv papers it cites
What it cites · 4 sentences without a confident label
Uses data or values from 2 papers
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lccccc Correlations among Abundance Ratios 0pt Cluster (References) 5cRatio Pair 2-6 [La/Fe] $+$ [Eu/Fe] [La/Fe] $+$ [Na/Fe] [Eu/Fe] $+$ [Na/Fe] M3 [ref] (0.64, 20, 0.00024) ($-$0.20, 20, 0.39) (0.12, 22, 0.60) M3 [ref] (0.35, 7, 0.45) ($-$0.21, 7, 0.65) ($-$0.24, 8, 0.57) M5 [ref] (0.43, 25, 0.034) ($-$0.25, 25, 0.22) ($-$0.16, 25, 0.45) M5 [ref] (0.80, 17, 0.00010) (0.10, 17, 0.70) (0.16, 17, 0.55) M12 [ref] (-0.31, 21, 0.17) ($-$0.37, 11, 0.26) (0.41, 11, 0.21) M13 [ref] (0.72, 18, 0.00066) ($-$0.51, 18, 0.029) ($-$0.40, 18, 0.099) M13 [ref] (0.07, 11, 0.83) ($-$0.23, 12, 0.47) (0.43, 12, 0.16) M15 [ref] (0.97, 6, 0.0011) M15 [ref] (0.89, 9, 0.0012) (0.02, 9, 0.95) ($-$0.12, 9, 0.77) M22 [ref] a ($-$0.07, 21, 0.75) ($-$0.13, 21, 0.56) (0.21, 21, 0.36) M80 [ref] (0.37, 8, 0.37) (0.23, 10, 0.52)b (0.66, 8, 0.075)b M92 [ref] (0.49, 16, 0.052) ($-$0.02, 13, 0.95) ($-$0.24, 12, 0.45) NGC 1
Heavy Element Dispersion in the Metal-Poor Globular Cluster M92 · Literature Data · 0.98
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lccccc Correlations among Abundance Ratios 0pt Cluster (References) 5cRatio Pair 2-6 [La/Fe] $+$ [Eu/Fe] [La/Fe] $+$ [Na/Fe] [Eu/Fe] $+$ [Na/Fe] M3 [ref] (0.64, 20, 0.00024) ($-$0.20, 20, 0.39) (0.12, 22, 0.60) M3 [ref] (0.35, 7, 0.45) ($-$0.21, 7, 0.65) ($-$0.24, 8, 0.57) M5 [ref] (0.43, 25, 0.034) ($-$0.25, 25, 0.22) ($-$0.16, 25, 0.45) M5 [ref] (0.80, 17, 0.00010) (0.10, 17, 0.70) (0.16, 17, 0.55) M12 [ref] (-0.31, 21, 0.17) ($-$0.37, 11, 0.26) (0.41, 11, 0.21) M13 [ref] (0.72, 18, 0.00066) ($-$0.51, 18, 0.029) ($-$0.40, 18, 0.099) M13 [ref] (0.07, 11, 0.83) ($-$0.23, 12, 0.47) (0.43, 12, 0.16) M15 [ref] (0.97, 6, 0.0011) M15 [ref] (0.89, 9, 0.0012) (0.02, 9, 0.95) ($-$0.12, 9, 0.77) M22 [ref] a ($-$0.07, 21, 0.75) ($-$0.13, 21, 0.56) (0.21, 21, 0.36) M80 [ref] (0.37, 8, 0.37) (0.23, 10, 0.52)b (0.66, 8, 0.075)b M92 [ref] (0.49, 16, 0.052) ($-$0.02, 13, 0.95) ($-$0.24, 12, 0.45) NGC 1
The two metallicity groups of the globular cluster M22: a chemical perspective · Literature Data · 0.98
Cites as support 1 paper
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M15 and M92 show an unmistakable star-to-star dispersion of material relative to Fe (e.g., [ref] ), which is uncorrelated with the light element dispersion (see also [ref] ).
Heavy Element Dispersion in the Metal-Poor Globular Cluster M92 · Introduction · 0.96
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