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Photospheric physical conditions before a two-ribbon solar flare

Published online by Cambridge University Press:  01 November 2006

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

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We present preliminary results of the study of the photospheric physical conditions about 30 minutes before the 2N/M2 two-ribbon solar flare. The soft X-ray enhancement, $H_{\alpha}$ brightening and microwave bursts occured prior to the flare. We demonstrate the semiempirical models of the preflaring photosphere fot two kernels of the future flare. These models derived from the inversion reproduce the spectral observations in seven Fraunhofer lines. The models consist of two atmospheres: the magnetic flux tube and its nonmagnetic surroundings. The inferred models show strong changes of the photospheric physical conditions in the preflare phase. The preheating was found in the flux tube. Upward motions of the surrounding photospheric material were revealed. Significant discrepancies of the flux-tube temperature and density are found for two sites of the future flare. The inner kernel located near the filament was cooler in the photosphere than the outer kernel.

Type
Contributed Papers
Copyright
© 2006 International Astronomical Union