A search for 6Li in stars with planets

Reddy, Bacham E.; Lambert, David L.; Laws, Chris; González, Guillermo; Covey, Kevin R.

doi:10.1046/j.1365-8711.2002.05682.x

Cited by 106 publications

(159 citation statements)

References 28 publications

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“…Israelian et al (2003) claimed the presence of a notable amount of 6 Li in the atmosphere of the planet host HD 82943. Yet Reddy et al (2002) did not find 6 Li in several of the eight stars that were identified in the literature as possible recipients of accreted terrestrial material, in addition to the star HD 219542 A, the planetless primary of a binary. Thus, in spite of a number of studies devoted to this topic, there is no consensus that SWP exhibit a decreased abundance distribution when compared to stars without planets, meaning the presence of planets may, or may not, affect the abundance or processing of lithium in stellar atmospheres.…”

Section: Introductionmentioning

confidence: 88%

A detailed study of lithium in 107 CHEPS dwarf stars

Pavlenko

Jenkins

Ivanyuk

et al. 2018

A&A

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Context. We report results from lithium abundance determinations using high resolution spectral analysis of the 107 metal-rich stars from the Calan-Hertfordshire Extrasolar Planet Search programme. Aims. We aim to set out to understand the lithium distribution of the population of stars taken from this survey. Methods. The lithium abundance taking account of non-local thermodynamical equilibrium effects was determined from the fits to the Li I 6708 Å resonance doublet profiles in the observed spectra. Results. We find that a) fast rotators tend to have higher lithium abundances; b) log N(Li) is higher in more massive and hot stars; c) log N(Li) is higher in stars of lower log g; d) stars with the metallicities >0.25 dex do not show the lithium lines in their spectra; e) most of our planet hosts rotate slower; and f) a lower limit of lithium isotopic ratio is 7 Li/ 6 Li > 10 in the atmospheres of two stars with planets (SWP) and two non-SWP stars. Conclusions. Measurable lithium abundances were found in the atmospheres of 45 stars located at distances of 20−170 pc from the Sun, for the other 62 stars the upper limits of log N(Li) were computed. We found well defined dependences of lithium abundances on T eff , V sin i, and less pronounced for the log g. In case of V sin i we see two sequences of stars: with measurable lithium and with the upper limit of log N(Li). About 10% of our targets are known to host planets. Only two SWP have notable lithium abundances, so we found a lower proportion of stars with detectable Li among known planet hosts than among stars without planets. However, given the small sample size of our planet-host sample, our analysis does not show any statistically significant differences in the lithium abundance between SWP and stars without known planets.

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Section: Introductionmentioning

confidence: 88%

A detailed study of lithium in 107 CHEPS dwarf stars

Pavlenko

Jenkins

Ivanyuk

et al. 2018

A&A

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“…For the former, we adopted the Reddy et al (2002) hyperfine structure. We also added to the linelist the two Fe I and Ti I lines at 6707.433 Å and 6708.125 Å, respectively, listed in Gonzalez et al (2009, hereafter G09).…”

Section: Chemical Abundance Analysismentioning

confidence: 99%

Lithium-rich giants in the Galactic thick disk

Monaco

Villanova

Bidin

et al. 2011

A&A

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Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12 C/ 13 C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 M star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12 C/ 13 C isotopic ratio, close to the cool bottom processing predictions.

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“…3 using the abundances given in Lecureur et al (2007). The log gf value for Ti I line at 6708.025 Å was modified from that adopted by Reddy et al (2002) as well as both V I lines at 6708.125 Å and 6708.280 Å. The final, calibrated atomic lines used in the synthesis are listed in Table 2.…”

Section: Linelistsmentioning

confidence: 99%

Li-rich red giant branch stars in the Galactic bulge

Gonzalez

Zoccali²,

Monaco

et al. 2009

A&A

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Aims. We present lithium abundance determination for a sample of K giant stars in the Galactic bulge. The stars presented here are the only 13 stars with a detectable lithium line (6767.18 Å) among ∼400 stars for which we have spectra in this wavelength range, half of them in Baade's Window (b = −4 • ) and half in a field at b = −6 • . Methods. The stars were observed with the GIRAFFE spectrograph of FLAMES mounted on VLT, with a spectral resolution of R ∼ 20 000. Abundances were derived from spectral synthesis and the results are compared with those of stars with similar parameters, but no detectable Li line. Results. We find 13 stars with a detectable Li line, among which 2 have abundances A(Li) > 2.7. No clear correlations were found between the Li abundance and those of other elements. With the exception of the two most Li rich stars, the others follow a fairly tight A(Li) − T eff correlation. Conclusions. There is strong indication of a Li production phase during the red giant branch (RGB), acting either on a very short timescale, or selectively only in some stars. That the proposed Li production phase is associated with the RGB bump cannot be excluded, although our targets are significantly brighter than the predicted RGB bump magnitude for a population at 8 kpc.

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A search for 6Li in stars with planets

Cited by 106 publications

References 28 publications

A detailed study of lithium in 107 CHEPS dwarf stars

A detailed study of lithium in 107 CHEPS dwarf stars

Lithium-rich giants in the Galactic thick disk

Li-rich red giant branch stars in the Galactic bulge

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