Origin of multiple stellar populations in globular clusters and their helium enrichment

By A. Renzini. 2008

150 citations recorded by the source corpus.

The various scenarios proposed for the origin of the multiple, helium-enriched populations in massive globular clusters are critically compared to the relevant constraining observations. Among accretion of helium-rich material by pre-existing stars, star formation out of ejecta from massive asymptotic giant branch (AGB) stars or from fast rotating massive stars, and pollution by Population III stars, only the AGB option appears to be viable. Accretion or star formation out of outflowing discs would result in a spread of helium abundances, thus failing to produce the distinct, chemically homogeneous subpopulations such as those in the clusters ω Cen and NGC 2808. Pollution by Population III stars would fail to produce subpopulations selectively enriched in helium, but maintaining the same abundance of heavy elements. Still, it is argued that for the AGB option to work, two conditions should be satisfied: (i) AGB stars experiencing the hot bottom burning process (i.e. those more massive than ∼ 3M � ) should rapidly eject their envelope upon arrival on the AGB, thus experiencing just a few third dredge-up episodes; and (ii) clusters with multiple, helium-enriched populations should be the remnants of much more massive systems, such as nucleated dwarf galaxies, as indeed widely assumed.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d0b1c0e7c1167799cbe3119f8da673321f24936a

How researchers see this paper

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In Astronomy and Astrophysics

1. R. Gratton
2. E. Carretta
3. Jay Anderson
4. A. Bragaglia
5. C. Conroy
6. G. Piotto
7. F. D’Antona
8. Hans-Walter Rix

In Instrumentation

1. E. Carretta
2. F. D’Antona
3. R. Gratton
4. A. Bragaglia
5. Jay Anderson
6. G. Piotto
7. L. Bedin
8. A. Milone

Citations in the corpus

• Updated stellar yields from asymptotic giant branch models (2009, background): “100 Myr) and are one of the stellar sites proposed as the polluters of globular clusters (Cottrell & Da Costa 1981; Gratton et al. 2004; Renzini 2008), even if quantitative problems with the models exist (e.g., Fenner et al. 2004).”
• Abundance patterns of multiple populations in globular clusters: a chemical evolution model based on yields from AGB ejecta (2010, background): “This led Renzini (2008) to argue that helium-rich material was accumulated in the ISM for a sufficient long time until suddenly a burst turned a major fraction of the ISM into stars.”
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy (2016, background): “…spreads were ascribed to the clusters’ intrinsic chemical evolution, either due to some form of feedback-regulated star formation history (e.g., Decressin et al. 2007; D’Ercole et al. 2008; Renzini 2008; Conroy & Spergel 2011) or to other processes (e.g., Bastian et al. 2013; Hopkins 2014).”
• CHEMICAL ABUNDANCES FOR 855 GIANTS IN THE GLOBULAR CLUSTER OMEGA CENTAURI (NGC 5139) (2010, background): “Additionally, the massive, rapidly rotating star scenario is expected to produce a continuum of polluted stars with varying He abundances (Renzini 2008), which is inconsistent with the singular Y=0.38 value that seems required to fit the blue main sequence (e.g., Piotto et al. 2005).”
• Multiple populations in globular clusters (2012, methodology): “In ∼ 3−8 M⊙ stars, He is brought to the envelope by the second dredge-up (Becker & Iben 1979, see also Ventura et al. 2002 and Renzini 2008), while the light elements are produced in p−capture reactions in hot bottom burning (Scalo et al. 1975; Blöcker & Schönberner 1991; Sackmann & Boothroyd…”
• The evolution of isotope ratios in the Milky Way Galaxy (2011, background): “AGB stars with HBB have short lifetimes (τ < ∼ 100 Myr) and are one of the stel- lar sites proposed as the polluters of globular clusters (e.g., Cottrell & Da Costa 1981; Renzini 2008), even if quantitative problems with the models exist (e.g., Fenner et al. 2004).”
• Massive binaries as the source of abundance anomalies in globular clusters (2009, background): “Finally, some peculiar feature, such as the apparent presenc of distinct, chemically homogeneous subpopulations inω Cen and NGC 2808 (e.g. Renzini 2008) deserves further attention.”
• THE AGES OF 55 GLOBULAR CLUSTERS AS DETERMINED USING AN IMPROVED METHOD ALONG WITH COLOR–MAGNITUDE DIAGRAM CONSTRAINTS, AND THEIR IMPLICATIONS FOR BROADER ISSUES (2013, background): “It should also be kept in mind that, as discussed in the extensive review by Gratton, Carretta, & Bragaglia (2012, also see Renzini 2008), current models for the AGB phase and for rapidly rotating massive stars (Decressin et al. 2007, and references therein) are not able to reproduce the observed…”
• Properties of stellar generations in globular clusters and relations with global parameters (2010, background): “…be regarded as the fingerprints of these different subpopulations, and may be used to get insight into the early phases of formation 1 The strong objection made by Renzini (2008) on the outflowing of matter from FRMS being unable to result in clearly separated MS with different – and discrete –”
• The Hubble Space TelescopeUV Legacy Survey of Galactic Globular Clusters – V. Constraints on formation scenarios (2015, background): “Indeed, the main metal rich component of this cluster contains just∼ 25M⊙ of additional iron compared to the iron content of the 1G component (Renzini 2008).”
• Ultralight scalars as cosmological dark matter (2016, background): “A more speculative concern is the origin of globular clusters (GCs), which remains mysterious.”
• THE HUBBLE SPACE TELESCOPE UV LEGACY SURVEY OF GALACTIC GLOBULAR CLUSTERS. I. OVERVIEW OF THE PROJECT AND DETECTION OF MULTIPLE STELLAR POPULATIONS (2014, background): “…D’Ercole et al. 2008, Ventura et al. 2014for estimates of the possible initial 1G cluster masses), and must have undergone a significant loss of 1G stars (see, e.g., D’Ercole et al. 2008, Decressin et al. 2010) leading to the large fraction of 2G stars currently observed in many GCs (Renzini 2008).”
• Photometric signatures of multiple stellar populations in galactic globular clusters (2011, background): “These currently discussed options are winds from massive stars or mass loss from intermediate mass stars during the thermally pulsing Asymptotic Giant Branch phase (AGB - see, e.g., Renzini 2008, and references therein).”
• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra (2009, background): “…whether the polluters of the first-generation contribued their enriched matter to the intra-cluster pool of gas in their m in sequence phase (as fast-rotating massive stars) or in a more evolved stage (as massive AGB stars): see Decressin et al. (2007), D’Antona & Ventura (2007), Renzini (2008).”