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The enigma of lithium in roAp stars

Published online by Cambridge University Press:  02 March 2005

N. Polosukhina
Affiliation:
Crimean Astrophysical Observatory, Ukraine email: polo@crao.crimea.ua
A. Shavrina
Affiliation:
Main Astronomical Observatory, National Academy of Science, Ukraine email: shavrina@mao.kiev.ua
N.A. Drake
Affiliation:
Observatório Nacional/MCT, Rio de Janeiro, Brazil email: drake@on.br Sobolev Astronomical Institute, St. Petersburg State University, Russia
V. Tsymbal
Affiliation:
Simferopol State University, Ukraine email: vad@ccssu.crimea.ua
M. Hack
Affiliation:
Department of Astronomy, Trieste University, Italy email: hack@ats.stro.it
P. North
Affiliation:
Institut d'Astronomy, Université de Lausanne, Switzerland email: pierre.north@obs.unige.ch
V. Khalack
Affiliation:
Main Astronomical Observatory, National Academy of Science, Ukraine email: shavrina@mao.kiev.ua
J. Zverko
Affiliation:
Astronomical Institute, Slovak Academy of Science, Slovakia email: zve@ta3.sk
J. Žižňovský
Affiliation:
Astronomical Institute, Slovak Academy of Science, Slovakia email: zve@ta3.sk
Ya. Pavlenko
Affiliation:
Main Astronomical Observatory, National Academy of Science, Ukraine email: shavrina@mao.kiev.ua
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Abstract

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An internacional project “Lithium in magnetic Ap stars” has been run since 1996 with the purpose of creating an observational database allowing systematic studies of the abnormal occurence of lithium on the surface of cool Ap stars. The 2.6 m telescope at the Crimean Astrophysical Observatory, the ESO CAT, ESO 1.52 m telescope with FEROS, the Nordic Optical Telescope, and the 74″ telescope at Mount Stromlo were employed to collect observations at the regions of the lithium resonance lines $\lambda 6103$ and $\lambda 6708 \AA$.

Observations of the roAp-stars HD 83368, HD 60435 and HD 3980 revealed considerable periodical Doppler shifts of the line of lithium $\lambda 6708 \AA$ which can be explained by the presence of lithium spots on their surfaces. Conjunction with structures of the magnetic field is apparent.

A detailed study of the blend at $\lambda 6708 \AA$ in HD 101065 confirmed the anomalous overabundance of lithium amounting to 3.1 dex, as well as unusual isotopic ratio $^6{\rm Li}/^7 {\rm Li} \sim 0.3$.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union