On the lithium abundance of the visual binary components $\xi$ Boo A (G8V) and $\xi$ Boo B (K5V)

Abstract

A spectroscopic investigation of the lithium resonance doublet in $\xi$ Boo A and $\xi$ Boo B in terms of both abundance and isotopic ratio is presented. We obtained new $R$=130\,000 spectra with a signal-to-noise ratio (S/N) per pixel of up to 3200 using the 11.8m LBT and PEPSI. From fits with synthetic line profiles based on 1D-LTE MARCS model atmospheres and 3D-NLTE corrections, we determine the abundances of both isotopes. For $\xi$ Boo A, we find A(Li) = 2.40$\pm$0.03\,dex and ${}^6$Li/${}^7$Li < 1.5$\pm$1.0\,\%\ in 1D-LTE, which increases to $\approx$2.45 for the 3D-NLTE case. For $\xi$ Boo B we obtain A(Li) = 0.37$\pm$0.09\,dex in 1D-LTE with an unspecified ${}^6$Li/${}^7$Li level. Therefore, no ${}^6$Li is seen on any of the two stars. We consider a spot model for the Li fit for $\xi$ Boo B and find A(Li) = 0.45$\pm$0.09\,dex. The ${}^7$Li abundance is 23 times higher for $\xi$ Boo A than the Sun's, but three times lower than the Sun's for $\xi$ Boo B while both fit the trend of single stars in the similar-aged M35 open cluster. Effective temperatures are redetermined from the TiO band head strength. We note that the best-fit global metallicities are --0.13$\pm$0.01\,dex for $\xi$ Boo A but +0.13$\pm$0.02\,dex for $\xi$ Boo B. Lithium abundance for the K5V benchmark star 61\,Cyg\,A was obtained to A(Li)$\approx$0.53\,dex when including a spot model but to $\approx$0.15\,dex without a spot model.

arXiv comment18 pages, 8 Figures, 7 Tables. Accepted by Astronomische Nachrichten / Astronomical Notes

References in corpus (33)

• Gaia Data Release 3: Summary of the content and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Chromospheric CaII Emission in Nearby F, G, K, and M stars
• Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog
• S4N: A Spectroscopic Survey of Stars in the Solar Neighborhood
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• ExoMol Molecular linelists -- XXXIII. The spectrum of Titanium Oxide
• Signatures of intrinsic Li depletion and Li-Na anti-correlation in the metal-poor globular cluster NGC6397
• Patterns of photometric and chromospheric variation among Sun-like stars: A 20-year perspective
• Mass-radius relation of low and very low-mass stars revisited with the VLTI
• The remarkable solar twin HIP 56948: a prime target in the quest for other Earths
• Abundances in the Local Region II: F, G and K Dwarfs and Subgiants
• WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-Aged Clusters. 1. Hyades & Praesepe
• Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands
• Abundance Analysis of Planetary Host Stars I. Differential Iron Abundances
• The photospheric solar oxygen project: IV. 3D-NLTE investigation of the 777 nm triplet lines
• The lithium-rotation connection in the 125 Myr-old Pleiades cluster
• A solar-like magnetic cycle on the mature K-dwarf 61 Cyg A (HD 201091)
• PEPSI deep spectra. I. The Sun-as-a-star
• Long-term magnetic field monitoring of the Sun-like star ξBootis A
• The radii of the nearby K5V and K7V stars 61 Cyg A & B - CHARA/FLUOR interferometry and CESAM2k modeling
• Large-scale magnetic field of the G8 dwarf xi Bootis A
• WIYN Open Cluster Study 5. Lithium Depletion and Metallicity in G and K Dwarfs of the Open Cluster M35
• A Search for ${}^6$Li in Lithium-Poor Stars with Planets
• A Chandra/LETGS Survey of Main Sequence Stars
• Another forbidden solar oxygen abundance: the [O I] 5577 A line
• Magnesium Isotopes in Metal-Poor Dwarfs, the Rise of AGB Stars and the Formation Timescale of the Galactic Halo
• Lithium abundance and 6Li/7Li ratio in the active giant HD123351 I. A comparative analysis of 3D and 1D NLTE line-profile fits
• PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards
• 3D non-LTE corrections for Li abundance and 6Li/7Li isotopic ratio in solar-type stars I. Application to HD 207129 and HD 95456
• Li in Open Clusters: Cool Dwarfs in the Young, Subsolar Metallicity Cluster M35 (NGC 2168)
• Improving spectroscopic lithium abundances. Fitting functions for 3D non-LTE corrections in FGK stars of different metallicity

Cited by in corpus (2)

• Zeeman Doppler Imaging of ksi Boo A and B
• VPNEP: Detailed characterization of TESS targets around the Northern Ecliptic Pole