Stellar Production of Lithium

Matteuccí, F.; D’Antona, Francesca; Timmes, F. X.

doi:10.1007/978-3-540-49169-9_53

Cited by 22 publications

(38 citation statements)

References 11 publications

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“…With those generous yields, D'Antona & Matteucci (1991) concluded that AGB stars were indeed important lithium producers. For similar assumptions, Matteucci et al (1995) obtained the same result. The present models, full evolutionary computations, and not educated guesses, on the contrary suggest that the lithium yields of massive AGBs are not so important (VDM00, Romano et al 2001).…”

Section: Rediscussion Of the Galactic Chemical Evolution Of Lithiumsupporting

confidence: 74%

Yields from low metallicity, intermediate mass AGB stars:

Ventura

D’Antona

Mazzitelli³

2002

A&A

146

216

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Abstract. We present the results of extensive computation of the Thermal Pulse phase AGB evolution of stars of metallicities in mass fraction 2 × 10 −4 ≤ Z ≤ 0.01, for those masses in the range 2.5 ≤ M/M ≤ 6, which suffer the Hot Bottom Burning (HBB) phase. The evolution is fully computed, by assuming a mass loss rate consistent with the observations of the Magellanic Clouds lithium-rich stars, and modelling convection with the Full Spectrum of Turbulence model by Canuto and Mazzitelli. The results are discussed in the framework of their importance for the evolution of proto-Globular Clusters, whose spectra show that the stars are very probably formed from matter contaminated by the ejecta of these stars, or have accreted it after formation. The main results we find are the following: 1) for metallicities Z ≤ 10 −3 , masses above ∼4 M suffer complete CNO cycling in HBB, so that they show at the surface the result of this process, and the oxygen abundance is reduced; 2) most models suffer the third dredge up. Although carbon is processed to nitrogen by HBB, the oxygen burning is so strong in the lowest metallicities (2 × 10 −4 ) that carbon becomes more abundant than oxygen: in other words, low-metallicity intermediate mass stars may show up as carbon stars due to the drastic oxygen burning; 3) if Globular Cluster stars are contaminated by matter processed through these phases, we must expect a non negligible helium enhancement in their composition: from a Big Bang abundance Y = 0.24, e.g., we might expect an abundance Y = 0.28. This may have no practical consequences if pollution concerns only the external parts of the stars, but is very important if the stars formed as a whole from a helium rich environment. 4) The lithium yields, although not important for galactic chemical evolution, are very interestingly close to the initial Big Bang abundance: processing by HBB is the only way in which we can obtain substantial amounts of gas which have gone through full CNO burning, but preserve a reasonable abundance of lithium.

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Section: Rediscussion Of the Galactic Chemical Evolution Of Lithiumsupporting

confidence: 74%

Yields from low metallicity, intermediate mass AGB stars:

Ventura

D’Antona

Mazzitelli³

2002

A&A

146

216

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“…Other possibilities for production of Li, such as in AGB stars or carbon stars (Matteucci et al 1995, Romano 1999, are shown not to reproduce the observations really as well as the delayed models, as one can see, for example, in Figure 4.…”

Section: Discussion : Alternative Sources Of Disk Lithiummentioning

confidence: 95%

“…Graphs common to all panels : Model due to Prantzos et al (1993) (dashed plus dotted line). Model due to Matteucci et al (1995) ( solid line) ; model with no disk production but with linearly time-dependent stellar depletion from a M _ "" primordial ÏÏ value of log N(Li)^3.5 (long-and short-dashed lines).…”

Section: Analytical and Semianalytical Models For The Temporal Evolutmentioning

confidence: 99%

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Production of Lithium in the Galactic Disk

Casuso

Beckman

2000

PUBL ASTRON SOC PAC

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ABSTRACT. The abundance of Li in stars formed within the past 5 Gyr is log N(Li) \ 3.2(^0.2), while the corresponding value for the oldest stars in the Galaxy is log N(Li) \ 2.2(^0.2). The global evidence suggests that the latter represents the full, or the major, part of the primordial abundance, so that the di †erence of an order of magnitude is due to Li produced in the Galaxy. It is well known that spallation of interstellar CNO by 4He and protons in Galactic cosmic rays (GCRs) can produce Li, but models yield a shortfall of almost an order of magnitude compared with the current observed abundance range. Another GCR reaction, a]a fusion, has been invoked to explain some Li production in the early Galaxy, but application of this to the disk yielded too much early Li or too little current Li. These failures led to a search for alternative mechanisms, essentially stellar, at particular phases of evolution : the helium Ñash phase in asymptotic giant branch stars, in novae, and in supernovae (SNe).Here we stress the importance of the observed upper envelope in the plot of Li versus Fe in stars as a constraint on any mechanism in any model aiming to account for disk Li. We show that a good match can be found assuming that low-energy GCRs produce the Li, with the a]a reaction as the key mechanism, although production in supernovae cannot at this stage be excluded. There is an apparent time delay in the Li production, relative to O and Fe, which if conÐrmed could be explained by the origin of a low-energy a-particle component in processes associated with stars of intermediate and low mass. The a-Ñux at a given epoch would then be proportional to the amount of gas expelled by low-and intermediate-mass stars in the Galaxy, though the acceleration of these a-particles could still be linked to more energetic events as supernova explosions. The present scenario appears to account coherently for the closely related observations of the temporal evolution in the Galaxy (halo]disk) of abundances of 12C, 13C, 14N, 16O, 26Fe, the two main peaks (one in the halo and one in the disk) in the G-dwarf stellar frequency distribution, and the evolution of 9Be and 10B]11B via GCR spallation reactions without requiring the very high local cosmicray Ñuxes implied by the spallation close to SN. Adding a natural mechanism of di †erential depletion in red supergiant envelopes, we can explain the observed time evolution of the abundance of D and that of the isotopic ratios 7Li/6Li and 11B/10B starting from a standard big bang nucleosynthesis model with baryon density D0.05. Our model also predicts the second Li "" plateau ÏÏ found for [Fe/H] between [0.2 and ]0.2, due to the "" loop back ÏÏ implied for Li (also for 9Be and B) because of the required infall of low-metallicity gas to the disk. Without ruling out other mechanisms for the main production of Li in the Galactic disk, the low-energy a]a fusion reaction in the interstellar medium o †ers a promising contribution.

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“…Although our procedure is not self-consistent, we seek here the maximum possible contribution of the WW95 yields to the Li abundance, to see if they violate any observational constraint (see also Matteucci et al 1995); results can be easily scaled downwards and even down to zero contribution from CCSN; 4) stellar sources other than CCSN, that is low-mass RGs, AGB stars, and novae. The situation has not evolved much since the extensive discussions in Travaglio et al (2001) and Romano et al (2001), which clearly show that the uncertainties in all those Li sources make any quantitative calculation of Li evolution almost meaningless.…”

Section: Evolution Of the Stellar Component Of LImentioning

confidence: 99%

Production and evolution of Li, Be, and B isotopes in the Galaxy

Prantzos

2012

A&A

166

159

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Context. We reassess the problem of the production and evolution of the light elements Li, Be and B and of their isotopes in the Milky Way in the light of new observational and theoretical developments. Aims. The main novelty is the introduction of a new scheme for the origin of Galactic cosmic rays (GCR), which for the first time enables a self-consistent calculation of their composition during galactic evolution. Methods. The scheme accounts for key features of the present-day GCR source composition, it is based on the wind yields of the Geneva models of rotating, mass-losing stars and it is fully coupled to a detailed galactic chemical evolution code. Results. We find that the adopted GCR source composition accounts naturally for the observations of primary Be and helps understanding why Be follows Fe more closely than O. We find that GCR produce ∼70% of the solar 11 B/ 10 B isotopic ratio; the remaining 30% of 11 B presumably result from ν-nucleosynthesis in massive star explosions. We find that GCR and primordial nucleosynthesis can produce at most ∼30% of solar Li. At least half of the solar Li has to originate in low-mass stellar sources (red giants, asymptotic giant branch stars, or novae), but the required average yields of those sources are found to be much higher than obtained in current models of stellar nucleosynthesis. We also present radial profiles of LiBeB elemental and isotopic abundances in the Milky Way disc. We argue that the shape of those profiles -and the late evolution of LiBeB in general -reveals important features of the production of those light elements through primary and secondary processes.

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Stellar Production of Lithium

Cited by 22 publications

References 11 publications

Yields from low metallicity, intermediate mass AGB stars:

Yields from low metallicity, intermediate mass AGB stars:

Production of Lithium in the Galactic Disk

Production and evolution of Li, Be, and B isotopes in the Galaxy

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