Age and mass of solar twins constrained by lithium abundance

Nascimento, J. D. do; Castro, M.; Meléndez, Jorge; Bazot, M.; Théado, S.; Mello, G. F. Porto de; Medeiros, J. R. De

doi:10.1051/0004-6361/200911935

Cited by 68 publications

(79 citation statements)

References 51 publications

(98 reference statements)

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“…With our radius measurement this gives a mass M = 1.02 ± 0.03 M for 18 Sco. The agreement is good with the published estimates derived from indirect methods, such as comparison between spectro-or photometric observations and stellar evolutionary tracks (Valenti & Fischer 2005;Meléndez & Ramírez 2007;Takeda et al 2007;Sousa et al 2008;do Nascimento et al 2009). …”

Section: Interferometrysupporting

confidence: 84%

The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry

Bazot

Ireland

Huber

et al. 2010

A&A

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The growing interest in solar twins is motivated by the possibility of comparing them directly to the Sun. To carry on this kind of analysis, we need to know their physical characteristics with precision. Our first objective is to use asteroseismology and interferometry on the brightest of them: 18 Sco. We observed the star during 12 nights with HARPS for seismology and used the PAVO beam-combiner at CHARA for interferometry. An average large frequency separation 134.4 ± 0.3 μHz and angular and linear radiuses of 0.6759 ± 0.0062 mas and 1.010 ± 0.009 R were estimated. We used these values to derive the mass of the star, 1.02 ± 0.03 M .

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Section: Interferometrysupporting

confidence: 84%

The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry

Bazot

Ireland

Huber

et al. 2010

A&A

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“…The depth of the surface convection zone and the nuclear burning depend strongly on the total stellar mass (do Nascimento et al 2009), thus the most appropriate way to investigate the abundance of lithium in these M 67 stars is first to divide our sample of stars in three different groups of mass range. MS stars with M ≤ 1.1 M , stars close to the turnoff with 1.1 M < M ≤ 1.28 M , and evolved sub-giant and giant stars with M > 1.28 M .…”

Section: Discussionmentioning

confidence: 99%

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

Pace

Castro

Meléndez

et al. 2012

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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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“…To investigate the evolutionary status, mass, and any correlation between Li abundance, convection, and rotation of solar-analog G dwarf stars, we computed a grid of hundreds of evolutionary models for stars of different metallicity and mass range, from 0.7 to 1.1 M . These evolutionary tracks were computed using the ToulouseGeneva code with updated physical inputs, as described in do Nascimento et al (2009). Our analysis of lithium abundance in a sample of solar-analog stars found different degrees of lithium depletion, a large scatter in the abundance being observed for stars over a narrow range of mass and metallicity.…”

Section: Discussionmentioning

confidence: 99%

“…Details about the underlying physics of these models can be found in Richard et al (1996), do Nascimento et al (2000, Hui-Bon-Hoa (2007), and do Nascimento et al (2009). Here, we provide a short description of the main physical stellar model ingredients.…”

Section: Stellar Evolutionary Modelsmentioning

confidence: 98%

“…Lithium data can be used to constrain the mass and metallicity-dependent process of the outer convective zone. Lithium depletion in solar-twins caused by non-standard mixing is strongly mass-dependent (do Nascimento et al 2009). A detailed comparison of the mass determinations of Takeda et al (2007) and Nordström et al (2004) reveals some discrepancies, such as HIP 45325.…”

Section: Working Samplementioning

confidence: 99%

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Rotation and lithium abundance of solar-analog stars

Nascimento¹,

Costa²,

Medeiros³

2010

A&A

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Context. Rotational velocity, lithium abundance, and the mass depth of the outer convective zone are key parameters in the study of the processes at work in the stellar interior, in particular when examining the poorly understood processes operating in the interior of solar-analog stars. Aims. We investigate whether the large dispersion in the observed lithium abundances of solar-analog stars can be explained by the depth behavior of the outer convective zone masses, within the framework of the standard convection model based on the local mixing-length theory. We also analyze the link between rotation and lithium abundance in solar-analog stars. Methods. We computed a new extensive grid of stellar evolutionary models, applicable to solar-analog stars, for a finely discretized set of mass and metallicity. From these models, the stellar mass, age, and mass depth of the outer convective zone were estimated for 117 solar-analog stars, using Teff and [Fe/H] available in the literature, and the new HIPPARCOS trigonometric parallax measurements. Results. We determine the age and mass of the outer convective zone for a bona fide sample of 117 solar-analog stars. No significant one-to-one correlation is found between the computed convection zone mass and published lithium abundance, indicating that the large A(Li) dispersion in solar analogs cannot be explained by the classical framework of envelope convective mixing coupled with lithium depletion at the bottom of the convection zone. Conclusions. These results illustrate the need for an extra-mixing process to explain lithium behavior in solar-analog stars, such as, shear mixing caused by differential rotation. To derive a more realistic definition of solar-analog stars, as well as solar-twin stars, it seems important to consider the inner physical properties of stars, such as convection, hence rotation and magnetic properties.

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Age and mass of solar twins constrained by lithium abundance

Cited by 68 publications

References 51 publications

The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry

The radius and mass of the close solar twin 18 Scorpii derived from asteroseismology and interferometry

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

Rotation and lithium abundance of solar-analog stars

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