Abundance analysis of three red giants in the metal-poor globular cluster NGC 2298

McWilliam, Andrew; Geisler, Doug; Rich, R. Michael

doi:10.1086/133108

Cited by 29 publications

(23 citation statements)

References 38 publications

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“…A.2) between dV and the rotational velocity (Col. 9 of Table A.1, where Θ = Θ−220) given by Dinescu et al (1999) and CasettiDinescu et al (2007), we replaced our dV values, when available, with the ones provided from those studies. Since we find that |dV| = (0.74 ± 0.06)|Θ |, the definition of y was in this case Carretta et al (2009b) ; (2) Shetrone & Keane (2000); (3) Yong & Grundahl (2008); (4) McWilliam et al (1992); (5) Shetrone et al (2001); (6) Ivans (2009); (7) Brown, et al (1997); (8) Sneden et al (2004); (9) McCarthy & Nemec (1997); (10) Lee et al (2006); (11) Smith et al 2002;(12) Cavallo et al (2004); (13) Lee & Carney (2002); (14) Sneden et al (2000); (15) Origlia et al (2005); (16) Lee (2007); (24) Marino et al (2009);(25) Brown et al (1999); (26) Fulton & Carney (1996); (27) Sbordone et al (2007); (28) Mottini et al (2008); (29) Kraft et al (1998); …”

Section: Appendix A: Classification Of Galactic Globular Clustersmentioning

confidence: 97%

Properties of stellar generations in globular clusters and relations with global parameters

Carretta¹,

Bragaglia²,

Gratton

et al. 2010

A&A

487

712

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We revise the scenario of the formation of Galactic globular clusters (GCs) by adding the observed detailed chemical composition of their different stellar generations to the set of their global parameters. We exploit the unprecedented set of homogeneous abundances of more than 1200 red giants in 19 clusters, as well as additional data from literature, to give a new definition of bona fide GCs, as the stellar aggregates showing the Na-O anticorrelation. We propose a classification of GCs according to their kinematics and location in the Galaxy in three populations: disk/bulge, inner halo, and outer halo. We find that the luminosity function of GCs is fairly independent of their population, suggesting that it is imprinted by the formation mechanism only marginally affected by the ensuing evolution. We show that a large fraction of the primordial population should have been lost by the proto-GCs. The extremely low Al abundances found for the primordial population of massive GCs indicate a very fast enrichment process before the formation of the primordial population. We suggest a scenario for the formation of GCs that includes at least three main phases: i) the formation of a precursor population (likely due to the interaction of cosmological structures similar to those that led to the formation of dwarf spheroidals, but residing at smaller Galactocentric distances, with the early Galaxy or with other structures); ii) the triggering of a long episode of star formation (the primordial population) from the precursor population; and iii) the formation of the current GC, mainly within a cooling flow formed by the slow winds of a fraction of the primordial population. The precursor population is very effective in raising the metal content in massive and/or metal-poor (mainly halo) clusters, while its rôle is minor in small and/or metal-rich (mainly disk) ones. Finally, we use principal component analysis and multivariate relations to study the phase of metal enrichment from first to second generation. We conclude that most of the chemical signatures of GCs may be ascribed to a few parameters, the most important being metallicity, mass, and cluster age. Location within the Galaxy (as described by the kinematics) also plays some rôle, while additional parameters are required to describe their dynamical status.

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Section: Appendix A: Classification Of Galactic Globular Clustersmentioning

confidence: 97%

Properties of stellar generations in globular clusters and relations with global parameters

Carretta¹,

Bragaglia²,

Gratton

et al. 2010

A&A

487

712

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show abstract

“…Following Ha10, we use the measured metallicities from McWilliam et al (1992) and to calculate the weighted [Fe/H] for NGC 2298. Our only knowledge of the chemical abundances in this cluster comes from McWilliam et al (1992), who analysed three of its RGB members. We therefore adopt their results for our compilation.…”

Section: A4 Ngc 2298mentioning

confidence: 99%

Constraining Stellar Population Models. I. Age, Metallicity and Abundance Pattern Compilation for Galactic Globular Clusters

Roediger

Courteau

Graves

et al. 2013

ApJS

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We present an extenstive literature compilation of age, metallicity, and chemical abundance pattern information for the 41 Galactic globular clusters (GGCs) studied by Schiavon et al. (2005). Our compilation constitutes a notable improvement over previous similar work, particularly in terms of chemical abundances. Its primary purpose is to enable detailed evaluations of and refinements to stellar population synthesis models designed to recover the above information for unresolved stellar systems based on their integrated spectra. However, since the Schiavon sample spans a wide range of the known GGC parameter space, our compilation may also benefit investigations related to a variety of astrophysical endeavours, such as the early formation of the Milky Way, the chemical evolution of GGCs, and stellar evolution and nucleosynthesis. For instance, we confirm with our compiled data that the GGC system has a bimodal metallicity distribution and is uniformly enhanced in the α-elements. When paired with the

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“…To these sets, we also added a full re-analysis of 3 giants in NGC 2298 (from McWilliam et al 1992;McW92), 18 stars studied by Minniti et al (1993;M 93) in 8 clusters, and 8 stars in 2 clusters from NDC. Table 5 lists the whole sample of globular clusters red giants analyzed in the present paper, with the source for each subset of data.…”

Section: Literature Datamentioning

confidence: 99%

Abundances for globular cluster giants. I. Homogeneous metallicities for 24 clusters

Carretta

Gratton

1997

Astron. Astrophys. Suppl. Ser.

628

662

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Abstract. We have obtained high resolution, high signalto-noise ratio CCD echelle spectra of 10 bright red giants in 3 globular clusters (47 Tuc, NGC 6752 and NGC 6397) roughly spanning the whole range of metallicities of the galactic globular cluster system. The analysis of this newly acquired material reveals no significant evidence of starto-star variation of the [Fe/H] ratio in these three clusters. Moreover, a large set of high quality literature data (equivalent widths from high dispersion CCD spectra) was reanalyzed in an homogeneous and self-consistent way to integrate our observations and derive new metal abundances for more than 160 bright red giants in 24 globular clusters (i.e. about 16% of the known population of galactic globulars). This set was then used to define a new metallicity scale for globular clusters which is the result of high quality, direct spectroscopic data, of new and updated model atmospheres from the grid of Kurucz (1992), and of a careful fine abundance analysis; this last, in turn, is based on a common set of both atomic and atmospheric parameters for all the stars examined. Given the very high degree of internal homogeneity, our new scale supersedes the offsets and discrepancies existing in previous attempts to obtain a metallicity scale. The internal uncertainty in [Fe/H] is very small: 0.06 dex (24 clusters) on average, and can be interpreted also as the mean precision of the cluster ranking. Compared to our system, metallicities on the widely used Zinn and West's scale are about 0.10 dex higher for [Fe/H]> −1, 0.23 dex lower for −1 <[Fe/H]< −1.9 and 0.11 dex too high for [Fe/H]< −1.9. The non-linearity of the Zinn and West's scale is significant even at 3σ level. A quadratic transformation is given to correct older values to the new scale in the range of our calibrating clusters (−2.24 ≤[Fe/H] ZW ≤ −0.51). A minor disagreement is found at low metallicities between the metallicity scale based on field and cluster RR Lyrae variables (via a new Send offprint requests to: E. Carretta Table 9 also available in electronic form at the CDS via anonymous ftp 130.79.128.5 or via http://cdsweb.ustrabg.fr/Abstract.html calibration of the ∆S index) and our new cluster metallicities. It could be tentatively ascribed to non-linearity in the [Fe/H]−∆S relationship. The impact of new metallicities on major astrophysical problems is exemplified through a simple exercise on the Oosterhoff effect in the classical pair M 3 and M 15.

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Abundance analysis of three red giants in the metal-poor globular cluster NGC 2298

Cited by 29 publications

References 38 publications

Properties of stellar generations in globular clusters and relations with global parameters

Properties of stellar generations in globular clusters and relations with global parameters

Constraining Stellar Population Models. I. Age, Metallicity and Abundance Pattern Compilation for Galactic Globular Clusters

Abundances for globular cluster giants. I. Homogeneous metallicities for 24 clusters

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