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Preflare chromospheric and photospheric line-of-sight velocities

Published online by Cambridge University Press:  14 March 2005

K. V. Alikaeva
Affiliation:
Main Astronomical Observatory, National Academy of Sciences of Ukraine, email: [email protected], [email protected] Present address: Main Astron. Observ., 27 Akademika Zabolotnoho St., 03680 Kyiv, Ukraine.
S. N. Chornogor
Affiliation:
Main Astronomical Observatory, National Academy of Sciences of Ukraine, email: [email protected], [email protected]
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Abstract

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The preflare plage spectra were obtained with the ATsU-26 solar telescope mounted at the Peak Terskol. The spectra were acquired from 1 h to 20 min before the flare onset. The most prominent peculiarity of all the observed events are the tilted $H_{\alpha}$-emission details which appear less than 40 min before the flare. This result may testify to spiral structure of the ascending $H_{\alpha}$ loops. The ascending velocities in the chromosphere attain more than 10 km/s. Two crossing $H_{\alpha}$ loops were observed to interact before 1n flare. As a result of their interaction, the redistribution of velocities occurs in the both chromosphere and photosphere. This can be a consequence of the preflare reconnection at the lower atmospheric layers. As the flare onset approaches the ascend of photospheric material start to dominate. The preflare line-of-sight velocities exceed considerably those in the neighbouring unperturbed regions.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