THE NEW DETECTIONS OF<sup>7</sup>Li/<sup>6</sup>Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

Kawanomoto, Satoshi; Kajino, Toshitaka; Aoki, Wako; Bessell, M. S.; Suzuki, Toshio; Ando, Hiroyasu; Noguchi, Kunio; Honda, Satoshi; Izumiura, Hideyuki; Kambe, Eiji; Sadakane, Kozo; Sato, B.; Tajitsu, Akito; Takada-Hidai, Masahide; Tanaka, Wataru; Watanabe, E.; Yoshida, Masaki

doi:10.1088/0004-637x/701/2/1506

Cited by 13 publications

(14 citation statements)

References 84 publications

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“…Observations of relatively low values of 7 Li/ 6 Li in interstellar matter near the supernova remnant IC 443 provide further evidence of recent lithium production by CR spallation and suggest that neutrino-induced spallation in the supernova event plays a minor role in lithium production (Taylor et al 2012). Other measurements of the lithium isotope ratio are taken as evidence of homogeneous mixing and rapid recycling of the interstellar gas (Kawanomoto et al 2009). …”

Section: Spallation and Synthesis Of Light Elementsmentioning

confidence: 99%

The Nine Lives of Cosmic Rays in Galaxies

Grenier

Black

Strong

2015

Annu. Rev. Astron. Astrophys.

314

294

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Cosmic-ray astrophysics has advanced rapidly in recent years, and its impact on other astronomical disciplines has broadened. Many new experiments, measuring the particles both directly in the atmosphere or space, and indirectly via γ rays and synchrotron radiation, have widened the range and quality of the information available on their origin, propagation, and interactions. The impact of low-energy cosmic rays on interstellar chemistry is a fast-developing topic, including the propagation of these particles into the clouds where the chemistry occurs. Cosmic rays, via their γ-ray production, also provide a powerful way to probe the gas content of the interstellar medium. Substantial advances have been made in the observations and modelling of the interplay between cosmic rays and the interstellar medium. Focussing on energies up to 1 TeV, these inter-relating aspects are covered at various levels of detail, giving a guide to the state of the subject. CONTENTS

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Section: Spallation and Synthesis Of Light Elementsmentioning

confidence: 99%

The Nine Lives of Cosmic Rays in Galaxies

Grenier

Black

Strong

2015

Annu. Rev. Astron. Astrophys.

314

294

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“…Additional 7 Li is produced by the same mechanism, and partly by stellar nucleosynthesis as well. The current 6 Li/ 7 Li ratio in the local interstellar medium (ISM) is measured to be ∼ 13% (Kawanomoto et al 2009, see also Howk et al 2012), while the solar system (meteoritic) 6 Li/ 7 Li ratio is 8.2% (Lodders 2003).…”

Section: Introductionmentioning

confidence: 99%

3D non-LTE corrections for Li abundance and⁶Li/⁷Li isotopic ratio in solar-type stars

Harutyunyan

Steffen

Mott

et al. 2018

A&A

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Context. Convective motions in solar-type stellar atmospheres induce Doppler shifts that affect the strengths and shapes of spectral absorption lines and create slightly asymmetric line profiles. One-dimensional (1D) local thermodynamic equilibrium (LTE) studies of elemental abundances are not able to reproduce this phenomenon, which becomes particularly important when modeling the impact of isotopic fine structure, like the subtle depression created by the 6 Li isotope on the red wing of the Li i resonance doublet line. Aims. The purpose of this work is to provide corrections for the lithium abundance, A(Li), and the 6 Li/ 7 Li ratio that can easily be applied to correct 1D LTE lithium abundances in G and F dwarf stars of approximately solar mass and metallicity for threedimensional (3D) and non-LTE (NLTE) effects. Methods. The corrections for A(Li) and 6 Li/ 7 Li are computed using grids of 3D NLTE and 1D LTE synthetic lithium line profiles, generated from 3D hydro-dynamical CO 5 BOLD and 1D hydrostatic model atmospheres, respectively. For comparative purposes, all calculations are performed for three different line lists representing the Li i λ670.8 nm spectral region. The 3D NLTE corrections are then approximated by analytical expressions as a function of the stellar parameters (T eff , log g, [Fe/H], v sin i, A(Li), 6 Li/ 7 Li). These are applied to adjust the 1D LTE isotopic lithium abundances in two solar-type stars, HD 207129 and HD 95456, for which high-quality HARPS observations are available. Results. The derived 3D NLTE corrections range between −0.01 and +0.11 dex for A(Li), and between −4.9 and −0.4% for the 6 Li/ 7 Li ratio, depending on the adopted stellar parameters. We confirm that the inferred 6 Li abundance depends critically on the strength of the Si i 670.8025 nm line. Our findings show a general consistency with recent works on lithium abundance corrections. After the application of such corrections, we do not find a significant amount of 6 Li in any of the two target stars. Conclusions. In the case of the 6 Li/ 7 Li ratio, our corrections are always negative, showing that 1D LTE analysis can significantly overestimate the presence of 6 Li (up to 4.9 percentage points) in the atmospheres of solar-like dwarf stars. These results emphasize the importance of reliable 3D model atmospheres combined with NLTE line formation for deriving precise isotopic lithium abundances. Although 3D NLTE spectral synthesis implies an extensive computational effort, the results can be made accessible with parametric tools like the ones presented in this work.

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“…Furthermore, observations of Li isotopic ratios became available, both in low-metallicity halo stars (Asplund et al 2006;Garcia-Perez et al 2009) and in the local ISM (Kawanomoto et al 2009). The former, suggesting a surprisingly high 6 Li/ 7 Li ratio in the early Galaxy, stimulated a large body of theoretical work (see Prantzos 2006b, and references therein) but remains controversial (Spite & Spite 2010, and references therein); the latter, combined to the well-known meteoritic ratio of 6 Li/ 7 Li, constrains the late evolution of Li isotopes in the local region of the Galaxy.…”

Section: Introductionmentioning

confidence: 99%

“…From the observational side, large surveys of Be in stars of low metallicities (Primas 2010;Tan et al 2009;Smiljianic et al 2009;Boesgaard et al 2011) considerably improved the statistics of the Be vs Fe, but also of Be vs. O relationships, providing combined and tighter constraints to models than those previously available. Furthermore, observations of Li isotopic ratios became available, both in lowmetallicity halo stars (Asplund et al 2006;Garcia-Perez et al 2009) and in the local ISM (Kawanomoto et al 2009). The former, suggesting a surprisingly high 6 Li/ 7 Li ratio in the early Galaxy, stimulated a large body of theoretical work (see Prantzos 2006b and references therein) but remains controversial (Spite and Spite 2010 and references therein); the latter, combined to the well-known meteoritic ratio of 6 Li/ 7 Li , constrains the late evolution of Li isotopes in the local region of the Galaxy.…”

Section: Introductionmentioning

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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THE NEW DETECTIONS OF⁷Li/⁶Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

Cited by 13 publications

References 84 publications

The Nine Lives of Cosmic Rays in Galaxies

The Nine Lives of Cosmic Rays in Galaxies

3D non-LTE corrections for Li abundance and⁶Li/⁷Li isotopic ratio in solar-type stars

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

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THE NEW DETECTIONS OF7Li/6Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

Cited by 13 publications

References 84 publications

The Nine Lives of Cosmic Rays in Galaxies

The Nine Lives of Cosmic Rays in Galaxies

3D non-LTE corrections for Li abundance and6Li/7Li isotopic ratio in solar-type stars

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

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Product

Resources

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THE NEW DETECTIONS OF⁷Li/⁶Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

3D non-LTE corrections for Li abundance and⁶Li/⁷Li isotopic ratio in solar-type stars