The Evolution of the Lithium Abundances of Solar-Type Stars. VIII. M67 (NGC 2682)

Jones, B. F.; Fischer, Debra A.; Soderblom, David R.

doi:10.1086/300664

Cited by 115 publications

(152 citation statements)

References 35 publications

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“…1 and 2), the lithium depletion progressively increases toward lower masses. A dispersion is observed in this mass range and confirmed by several authors (Pasquini et al 1997;Jones et al 1999;Randich et al 2002Randich et al , 2007Pasquini et al 2008). We note that in this region, some upper limits used may be considered as too optimistic.…”

Section: Lithium Abundance and Masssupporting

confidence: 88%

Lithium in M 67: From the main sequence to the red giant branch

Pace

Castro

Meléndez

et al. 2012

A&A

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Context.Lithium abundances in open clusters are a very effective probe of mixing processes, and their study can help us to understand the large depletion of lithium that occurs in the Sun. Owing to its age and metallicity, the open cluster M 67 is especially interesting on this respect. Many studies of lithium abundances in M 67 have been performed, but a homogeneous global analysis of lithium in stars from subsolar masses and extending to the most massive members, has yet to be accomplished for a large sample based on high-quality spectra. Aims. We test our non-standard models, which were calibrated using the Sun with observational data. Methods.We collect literature data to analyze, for the first time in a homogeneous way, the non-local thermal equilibrium lithium abundances of all observed single stars in M 67 more massive than ∼0.9 M . Our grid of evolutionary models is computed assuming a non-standard mixing at metallicity [Fe/H] = 0.01, using the Toulouse-Geneva evolution code. Our analysis starts from the entrance into the zero-age main-sequence. Results. Lithium in M 67 is a tight function of mass for stars more massive than the Sun, apart from a few outliers. A plateau in lithium abundances is observed for turn-off stars. Both less massive (M ≤ 1.10 M ) and more massive (M ≥ 1.28 M ) stars are more depleted than those in the plateau. There is a significant scatter in lithium abundances for any given mass M ≤ 1.1 M . Conclusions. Our models qualitatively reproduce most of the features described above, although the predicted depletion of lithium is 0.45 dex smaller than observed for masses in the plateau region, i.e. between 1.1 and 1.28 solar masses. More work is clearly needed to accurately reproduce the observations. Despite hints that chromospheric activity and rotation play a role in lithium depletion, no firm conclusion can be drawn with the presently available data.

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Section: Lithium Abundance and Masssupporting

confidence: 88%

Lithium in M 67: From the main sequence to the red giant branch

Pace

Castro

Meléndez

et al. 2012

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“…Previous Li observations in M 67 stars show that a real dispersion in the lithium abundance of main-sequence objects exists even though at this phase the convective envelope is too superficial to reach the layer where Li destruction can occur (Pasquini et al 1997;Jones et al 1999;Randich et al 2002Randich et al , 2007. While standard models appeared inefficient to explain this Li dispersion observed in unevolved M 67 stars, the rotational mixing seems to be a good candidate (Pasquini et al 1997).…”

Section: Introductionmentioning

confidence: 94%

Lithium abundances and extra mixing processes in evolved stars of M 67

Martins

Lebre

Palacios

et al. 2011

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Aims. We present a spectroscopic analysis of a sample of evolved stars in M 67 (turn-off, subgiant and giant stars) in order to bring observational constraints to evolutionary models taking into account non-standard transport processes. Methods. We determined the stellar parameters (T eff , log g, [Fe/H]), microturbulent and rotational velocities and, lithium abundances (A Li ) for 27 evolved stars of M 67 with the spectral synthesis method based on MARCS model atmospheres. We also computed non-standard stellar evolution models, taking into account atomic diffusion and rotation-induced transport of angular momentum and chemicals that were compared with this set of homogeneous data. Results. The lithium abundances that we derive for the 27 stars in our sample follow a clear evolutionary pattern ranging from the turn-off to the Red Giant Branch. Our abundance determination confirms the well known decrease of lithium content for evolved stars. For the first time, we provide a consistent interpretation of both the surface rotation velocity and of the lithium abundance patterns observed in an homogeneous sample of TO and evolved stars of M 67. We show that the lithium evolution is determined by the evolution of the angular momentum through rotation-induced mixing in low-mass stars, in particular for those with initial masses larger than 1.30 M when at solar metallicity.

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“…Most likely, the Li in these metal-rich stars represent abundances that were obtained by depletion during their mainsequence lifetimes from higher initial values. Observations of intermediate-age solar-metallicity stars both in clusters such as M 67 (e.g., Jones et al 1999) and in the field (e.g., Baumann et al 2010) show that they have a large range of Li values, which can be explained by a range of ages, masses, and initial rotation values.…”

Section: Lithium Abundances In the Bulgementioning

confidence: 99%