Isotopic Lithium Abundances in Nine Halo Stars

Smith, Verne V.; Lambert, David L.; Nissen, P. E.

doi:10.1086/306238

Cited by 190 publications

(232 citation statements)

References 45 publications

Supporting

Mentioning

202

Contrasting

Order By: Relevance

“…The problem with this isotope is that detections for metal-poor stars are very challenging and very rare. Smith et al (1993) reported the first probable detection of 6 Li in HD 84937 ( 6 Li/ 7 Li = 0.05 ± 0.02) which was later confirmed by other works (Hobbs & Thorburn 1994;Smith et al 1998;Cayrel et al 1999). A few years after this first detection, a detection for another star, BD +26 • 3578 ( 6 Li/ 7 Li = 0.05 ± 0.03, Smith et al 1998), was reported.…”

Section: Introductionsupporting

confidence: 54%

“…Smith et al (1993) reported the first probable detection of 6 Li in HD 84937 ( 6 Li/ 7 Li = 0.05 ± 0.02) which was later confirmed by other works (Hobbs & Thorburn 1994;Smith et al 1998;Cayrel et al 1999). A few years after this first detection, a detection for another star, BD +26 • 3578 ( 6 Li/ 7 Li = 0.05 ± 0.03, Smith et al 1998), was reported. Possible detections for two other stars were provided by Cayrel et al (1999) and Nissen et al (2000): BD+42 • 2667 ( 6 Li/ 7 Li = 0.10) and G 271-162 ( 6 Li/ 7 Li = 0.02 ± 0.01) respectively.…”

Section: Introductionsupporting

confidence: 54%

See 1 more Smart Citation

⁶Li/⁷Li estimates for metal-poor stars

Pérez¹,

Aoki

Inoue³

et al. 2009

A&A

View full text Add to dashboard Cite

Context. The presence of the lithium-6 isotope in some metal-poor stars is a matter of surprise because of the high values observed. Non-standard models of Big Bang nucleosynthesis and pre-Galactic cosmic ray fusion and spallation have been proposed to explain these values. However, the observations of this light isotope are challenging which may make some detections disputable. Aims. The goal was to determine 6 Li/ 7 Li for a sample of metal-poor stars; three of them have been previously studied and the remaining two are new for this type of study. The purpose was to increase, if possible, the number of lithium-6 detections and to confirm previously published results.Methods. Spectra of the resonance doublet line of neutral lithium Li i 670.78 nm were taken with the high dispersion spectrograph at the Subaru 8.2 m-telescope for a sample of five metal-poor stars (−3.12 ≤ [Fe/H] ≤ −2.19). The contribution of lithium-6 to the total observed line profile was estimated from the 1D-LTE analysis of the line asymmetry. Results. Observed asymmetries could be reproduced assuming isotopic abundance ratios 6 Li/ 7 Li of the order of: 0.004 for BD +26 • 3578, ∼0.010 for BD +02 • 3375 and G 64-37, 0.025 for BD +20 • 3603 and 0.047 for BD −04 • 3208. We found that these results were very sensitive to several of the assumptions made in the analysis, in particular, the treatment of the residual structure in the analysed spectra. Our final estimates for the errors are respectively Δ 6 Li/ 7 Li = ±0.028, 0.029, 0.039, 0.025 and 0.039. Conclusions. The 6 Li/ 7 Li ratios for the sample are comparable to or even lower than these error values, so that detections of lithium-6 can not safely be claimed despite of the high resolving power (R ∼ 95 000) and S /N (400−600).

show abstract

Section: Introductionsupporting

confidence: 54%

Section: Introductionsupporting

confidence: 54%

⁶Li/⁷Li estimates for metal-poor stars

Pérez¹,

Aoki

Inoue³

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…The lithium abundance was determined using the accurate laboratory atomic data of Smith et al (1998). A solar isotopic ratio 7 Li/ 6 Li = 12.18 was adopted ).…”

Section: Methods Of Analysismentioning

confidence: 99%

Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy

Morel

Rainer

Poretti

et al. 2013

A&A

View full text Add to dashboard Cite

We present a detailed abundance study based on spectroscopic data obtained with HARPS of two solar-analogue main targets for the asteroseismology programme of the CoRoT satellite: HD 42618 and HD 43587. The atmospheric parameters and chemical composition are accurately determined through a fully differential analysis with respect to the Sun observed with the same instrumental set-up. Several sources of systematic errors largely cancel out with this approach, which allows us to narrow down the 1-σ error bars to typically 20 K in effective temperature, 0.04 dex in surface gravity, and less than 0.05 dex in the elemental abundances. Although HD 42618 fulfils many requirements for being classified as a solar twin, its slight deficiency in metals and its possibly younger age indicate that, strictly speaking, it does not belong to this class of objects. On the other hand, HD 43587 is slightly more massive and evolved. In addition, marked differences are found in the amount of lithium present in the photospheres of these two stars, which might reveal different mixing properties in their interiors. These results will put tight constraints on the forthcoming theoretical modelling of their solar-like oscillations and contribute to increase our knowledge of the fundamental parameters and internal structure of stars similar to our Sun.

show abstract

“…The g f values of the Li lines are among the most accurate for any stellar lines (Smith et al 1998), and can safely be used in an absolute manner. The result is A(Li) = −10.84±0.10 and −11.19 ± 0.13 for HD 27536 and HD 216803, respectively, the errors coming primarily from uncertainty in the continuum placement and the influence from the weak Fe i, V i, and CN blends.…”

Section: Notes On Individual Abundancesmentioning

confidence: 99%

Binarity, activity and metallicity among late-type stars

Dall¹,

Bruntt²,

Strassméier

2005

A&A

View full text Add to dashboard Cite

We present the first in a series of papers that attempt to investigate the relation between binarity, magnetic activity, and chemical surface abundances of cool stars. In the current paper, we lay out and test two abundance analysis methods and apply them to two well-known, active, single stars, HD 27536 (G8IV-III) and HD 216803 (K5V), presenting photospheric fundamental parameters and abundances of Li, Al, Ca, Si, Sc, Ti, V, Cr, Fe, Co and Ni. The abundances from the two methods agree within the errors for all elements except calcium in HD 216803, which means that either method yields the same fundamental model parameters and the same abundances. Activity is described by the radiative loss in the Ca ii H and K lines with respect to the bolometric luminosity, through the activity index R HK . Binarity is established by very precise radial velocity (RV) measurements using HARPS spectra. The spectral line bisectors are examined for correlations between RV and bisector shape to distinguish between the effects of stellar activity and unseen companions. We show that HD 27536 exhibit RV variations mimicking the effect of a low-mass (m ∼ 4 M J ) companion in a relatively close (a ∼ 1 AU) orbit. The variation is strongly correlated with the activity, and consistent with the known photometric period P = 306.9 d, demonstrating a remarkable coherence between R HK and the bisector shape, i.e. between the photosphere and the chromosphere. We discuss the complications involved in distinguishing between companion and activity induced RV variations.

show abstract

Isotopic Lithium Abundances in Nine Halo Stars

Cited by 190 publications

References 45 publications

⁶Li/⁷Li estimates for metal-poor stars

⁶Li/⁷Li estimates for metal-poor stars

Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy

Binarity, activity and metallicity among late-type stars

Contact Info

Product

Resources

About

Isotopic Lithium Abundances in Nine Halo Stars

Cited by 190 publications

References 45 publications

6Li/7Li estimates for metal-poor stars

6Li/7Li estimates for metal-poor stars

Abundance study of the two solar-analogue CoRoT targets HD 42618 and HD 43587 from HARPS spectroscopy

Binarity, activity and metallicity among late-type stars

Contact Info

Product

Resources

About

⁶Li/⁷Li estimates for metal-poor stars

⁶Li/⁷Li estimates for metal-poor stars