Periodic variations of the Ba II 4554 Å and Ca II 8542 Å line profiles in coronal holes |
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| Authors: | N I Kobanov S A Chupin D Yu Kolobov |
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| Institution: | 1. Institute for Solar–Terrestrial Physics, Russian Academy of Sciences, Siberian Branch, P.O. Box 291, Irkutsk, 664033, Russia
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| Abstract: | The oscillations of the half-width of the Ba II 4554 ? and Ca II 8542 ? spectral lines have been analyzed using observations at the base of solar coronal holes (CHs). The observed variations (~50 m ? for Ca II and ~4 m ? for Ba II) exceed considerably the thermal broadenings of these lines calculated from the measured intensity oscillations, suggesting their nonthermal nature. We point out a number of observational facts that hamper an unambiguous interpretation of the periodic Ba II and Ca II profile variations solely by the manifestation of torsional Alfve´ n waves in the lower solar atmosphere. |
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