Lithium Abundances in Wide Binaries with Solar-Type Twin Components
We present high-resolution spectroscopic observations of the Li Iresonance line in a sample of 62 stars that belong to 31 common propermotion pairs with twin F- or G-type components. Photospheric abundancesof lithium were derived by spectral synthesis analysis. For seven of thepairs, we have measured large lithium abundance differences. Elevenother pairs have components with similar lithium abundances. We cannotdetermine if the remaining 13 pairs have lithium differences because wedid not detect the Li I lines, and hence we can only provide upperlimits to the abundances of both stars. Our results demonstrate thattwin stars do not always share the same lithium abundances. Lithiumdepletion in solar-type stars does not only depend on age, mass, andmetallicity. This result is consistent with the spread in lithiumabundances among solar-type stars in the solar-age open cluster M67. Ourstars are brighter than the M67 members of similar spectral type, makingthem good targets for detailed follow-up studies that could shed lighton the elusive mechanism responsible for the depletion of lithium duringthe main-sequence evolution of the Sun and solar-type stars.
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Analysis of the spectra of two solar-like binaries
Procedure and results of Li, Ca, Al, Si, and Fe abundance determinationsin the atmospheres of the solar-type components of the binaries HD 6872A, HD 6872 B and HD 224984, HD 224994 are described. These stars aredwarfs of spectral types G and F. Synthetic spectrum method was used toanalyse their spectra. Kurucz's (2000) model atmospheres ofmetallicities [mu] = 0...-0.2 and the atomic line list VALD veryfied bythe solar spectrum are used for computations of the synthetic spectra.Theoretical spectra were fitted to the observed HD 6872 A, HD 6872 B andHD 224984, HD 224994 spectra (lambda/deltalambda = 55000). We determinedthe same lithium abundances (logN(Li) = 2.3) in the atmospheres of HD224984 and HD 224994. For HD 6872 A and HD 6872 B we determineddifferent lithium abundances- logN(Li)<1.8, and logN(Li) = 2.6,respectively. For HD 6872 A we determined vsin i = 14 km/s.
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Photoelectric observations of CPM stars in the BVRI system
A photometric program to estimate the frequency of close unresolvedcompanions in visual binary systems has been developed. The sensitivityof the detection depends on the accuracy of the differential photometricmeasurements of binary components. Unresolved companions up to sevenmagnitudes fainter than the primary are detectable in the BVRIphotometric systems.
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Micrometer Observations of Double Stars and New Pairs - Part Ten
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1980ApJS...44..111H&db_key=AST
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Micrometer observations of double stars.8.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1975ApJS...29..315H&db_key=AST
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Micrometric Measures of Double Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974ApJS...28..413V&db_key=AST
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Mesures d'étoiles doubles visuelles
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970A&AS....3...71M&db_key=AST
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A list of stars with common proper motions.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1958AJ.....63..246V&db_key=AST
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