Li in Open Clusters: Cool Dwarfs in the Young, Subsolar-metallicity Cluster M35 (NGC 2168)<sup>*</sup>

Anthony-Twarog, Barbara J.; Deliyannis, Constantine P.; Harmer, Dianne; Lee-Brown, Donald B.; Steinhauer, A.; Sun, Qiwei; Twarog, Bruce A.

doi:10.3847/1538-3881/aacb1f

Cited by 24 publications

(16 citation statements)

References 95 publications

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“…Therefore, the main conclusion of this study is that we do not see any evidence of a decrease in Li at supersolar metallicity. Rather, the opposite might be true, and the data may suggest a positive Li versus [Fe/H] trend, in agreement with the suggestions of Anthony-Twarog et al (2018). Whilst a Bayesian analysis also supports a positive Li versus Fe correlation, this needs to be confirmed with a larger number of clusters, in particular young ones in the metal-poor regime.…”

Section: Resultssupporting

confidence: 75%

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

Randich

Pasquini

Franciosini

et al. 2020

A&A

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Context. Reconstructing the Galactic evolution of lithium (Li) is the main tool used to constrain the source(s) of Li enrichment in the Galaxy. Recent results have suggested a decline in Li at supersolar metallicities, which may indicate reduced production. Aims. We exploit the unique characteristics of the Gaia-ESO Survey open star cluster sample to further investigate this issue and to better constrain the evolution of Li at high metallicity. Methods. We trace the upper envelope of Li abundance versus metallicity evolution using 18 clusters and considering members that should not have suffered any Li depletion. Results. At variance with previous claims, we do not find any evidence of a Li decrease at high metallicity. The most metal-rich clusters in the sample ([Fe/H] = ∼0.3) actually show the highest Li abundances, with A(Li) > 3.4. Our results clearly show that previous findings, which were based on field stars, were affected by selection effects. The metal-rich population in the solar neighbourhood is composed of relatively old and cool stars that have already undergone some Li depletion; hence, their measured Li does not represent the initial interstellar medium abundance, but a lower limit to it.

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Section: Resultssupporting

confidence: 75%

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

Randich

Pasquini

Franciosini

et al. 2020

A&A

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“…As for cooler, lower-mass stars, in intermediate-age clusters, recent WOCS observations of M35 have shown that this cluster behaves similarly to the younger Pleiades, since a dispersion in Li is seen among cool stars, as well as a relationship with rotation and radii (Anthony- Twarog et al, 2018a;Jeffries et al, 2020); this, on the one hand, provides some support for models with inflated radii and lower Li depletion in the faster rotators (more active stars), as discussed above. At the same time, the authors claim that rotational mixing cannot be excluded: given the saturation of magnetic activity, stars would have similar levels of activity, and Li depletion during the PMS may be inhibited for all of them, while additional mixing would subsequently deplete more Li in slow rotators that undergo angular momentum loss (Jeffries et al, 2020).…”

Section: The Ms Phasesmentioning

confidence: 99%

“…b than 1 Gyr. The main recent results on Li evolution during the MS have been summarized byTwarog et al (2020) (see alsoDeliyannis et al, 2019;Anthony-Twarog et al, 2018a, Anthony-…”

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confidence: 97%

Light Elements in the Universe

Randich

Magrini

2021

Front. Astron. Space Sci.

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Due to their production sites, as well as to how they are processed and destroyed in stars, the light elements are excellent tools to investigate a number of crucial issues in modern astrophysics: from stellar structure and non-standard processes at work in stellar interiors to age dating of stars; from pre-main sequence evolution to the star formation histories of young clusters and associations and to multiple populations in globular clusters; from Big Bang nucleosynthesis to the formation and chemical enrichment history of the Milky Way Galaxy and its populations, just to cite some relevant examples. In this paper, we focus on lithium, beryllium, and boron (LiBeB) and on carbon, nitrogen, and oxygen (CNO). LiBeB are rare elements, with negligible abundances with respect to hydrogen; on the contrary, CNO are among the most abundant elements in the Universe, after H and He. Pioneering observations of light-element surface abundances in stars started almost 70 years ago and huge progress has been achieved since then. Indeed, for different reasons, precise measurements of LiBeB and CNO are difficult, even in our Sun; however, the advent of state-of-the-art ground- and space-based instrumentation has allowed the determination of high-quality abundances in stars of different type, belonging to different Galactic populations, from metal-poor halo stars to young stars in the solar vicinity and from massive stars to cool dwarfs and giants. Noticeably, the recent large spectroscopic surveys performed with multifiber spectrographs have yielded detailed and homogeneous information on the abundances of Li and CNO for statistically significant samples of stars; this has allowed us to obtain new results and insights and, at the same time, raise new questions and challenges. A complete understanding of the light-element patterns and evolution in the Universe has not been still achieved. Perspectives for further progress will open up soon thanks to the new generation instrumentation that is under development and will come online in the coming years.

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“…On average, the older the star the worse the discrepancy, with the Sun being one of the most egregious offenders, having depleted a factor of 50 more Li than the factor of ∼ 3 predicted by the SSET (King et al 1997;Pinsonneault 1997;Asplund et al 2009;Thévenin et al 2017). Another example is that of lower mass stars in the pre-main sequence and early MS phase, which exhibit large dispersions in Li at the same mass and age, with rapid rotators exhibiting higher Li abundances (Somers & Pinsonneault 2014Bouvier et al 2018;Anthony-Twarog et al 2018b). A particularly distressing example is F dwarfs, in which deep envelope SCZs should not exist.…”

Section: Introductionmentioning

confidence: 99%

Li Evolution and the Open Cluster NGC 6819: A Correlation between Li Depletion and Spindown in Dwarfs More Massive Than the F-Dwarf Li-Dip^*

Deliyannis

Anthony-Twarog

Lee-Brown

et al. 2019

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Spectroscopy of 333 NGC 6819 stars and Gaia astrometry are used to map Li evolution from the giant branch tip to 0.5 mag below the Li dip. Isochrone comparison with [F e/H] = −0.04, based upon neural network spectroscopic analysis, produces an age of 2.25 (2.4) Gyr for E(B − V ) = 0.16 (0.14) and (m − M ) = 12. 40 (12.29). Despite originating outside the Li dip, only 10% of single subgiants/giants have measurable Li. Above the Li dip, the limiting A(Li) for single stars is 3.2 ± 0.1 but the lower range is comparable to that found within the dip. The F-dwarf Li dip profile agrees with the Hyades/Praesepe, evolved forward. The Li level among stars populating the plateau fainter than the Li dip is A(Li) = 2.83 ± 0.16; the dispersion is larger than expected from spectroscopic error alone. Comparison of Li and V ROT distributions among turnoff stars in NGC 7789, NGC 2506, NGC 3680, and NGC 6819 indicates that rotational spindown from the main sequence is critical in defining the boundaries of the Li dip. For higher mass dwarfs, spindown is likewise correlated with Li depletion, creating a second dip, but at higher mass and on a longer time scale. The Li distribution among evolved stars of NGC 6819 is more representative of the older M67, where subgiant and giant stars emerge from within the Li dip, than the younger NGC 7789, where a broad range in V ROT among the turnoff stars likely produces a range in mass among the giants.

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Li in Open Clusters: Cool Dwarfs in the Young, Subsolar-metallicity Cluster M35 (NGC 2168)^*

Cited by 24 publications

References 95 publications

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

Light Elements in the Universe

Li Evolution and the Open Cluster NGC 6819: A Correlation between Li Depletion and Spindown in Dwarfs More Massive Than the F-Dwarf Li-Dip^*

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Li in Open Clusters: Cool Dwarfs in the Young, Subsolar-metallicity Cluster M35 (NGC 2168)*

Cited by 24 publications

References 95 publications

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

The Gaia-ESO Survey: Galactic evolution of lithium at high metallicity

Light Elements in the Universe

Li Evolution and the Open Cluster NGC 6819: A Correlation between Li Depletion and Spindown in Dwarfs More Massive Than the F-Dwarf Li-Dip*

Contact Info

Product

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Li in Open Clusters: Cool Dwarfs in the Young, Subsolar-metallicity Cluster M35 (NGC 2168)^*

Li Evolution and the Open Cluster NGC 6819: A Correlation between Li Depletion and Spindown in Dwarfs More Massive Than the F-Dwarf Li-Dip^*