Stellar activity in barium stars .1. Analysis of H-lines and K-lines CA-II-lines in 10 barium stars
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1992
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IOP Publishing ltd
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Abstract
High dispersion spectra have been obtained in order to study the activity level of ten barium stars by means of the Ca II H and K emission flux, looking for a relation between barium intensity index and activity. Absolute magnitudes obtained from the Wilson-Bappu relationship disagree, in some cases, with the magnitudes computed from parallaxes, but this fact is not due to barium nature. Total emission fluxes, F(H + K) or R_HK index, plotted versus effective temperature show a distribution similar to that of cool giant stars. The asymmetry of K emission line, [F(K_2ν)/F(K_2r)], has been analyzed in relation with effective temperature, in this sense barium stars behave as expected of late-type giants with the only exception of two stars.
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© 1992. American Astronomical Society.
The 2.2 m telescope at Calar Alto Observatory is operated by the Max-Planck Institut für Astronomie at the Centro Astronómico Hispano-Alemán. We want to express our gratitude to the staff of the Observatory for their help during the observational campaign. This work has been supported by the Spanish Comisión Interministerial de Ciencia y Tecnología.