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Astron. Astrophys. 317, 248-253 (1997)


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Was the flare on 5 July 1989 a white light flare?

K.J. Li 1, 2 and S.H. Zhong 2

1 CCAST (World Laboratory), P.O. Box 8730, Beijing 100080, China
2 Yunnan Observatory, Chinese Academy of Sciences, Yunnan 650011, China

Received 18 July 1994 / Accepted 27 October 1996

Abstract

The continuous emission spectra of H [FORMULA], H [FORMULA], and H tex2html_wrap_inline85 wave bands of the solar flare of 5 July 1989 have been analysed. We demonstrate that the flare not only emits at the line centres and wings of H [FORMULA], H [FORMULA], and H [FORMULA], but also in the continuum near these lines. The positions, durations, and configurations of the four flare kernels are respectively similar to those of a white light flare (WLF). Therefore we conclude that this flare was very likely a WLF. The magnetic field of the active region has also been analysed. Most of the flare is located in the vicinity of the neutral line of the magnetic field. Three of the four flare kernels that have continuous emissions lie in the penumbrae of the preceding sunspot and the following sunspot, and near the neutral line, where the magnetic field shears, twists, and shows evidences of having been squeezed or compressed. The fourth kernel of the flare is located in the photospheric region near a small sunspot (about [FORMULA] in size). The flare kernel with the brightest continuous emission is located at a point where the gradient of the longitudinal magnetic field has maximum value (0.52 Gs/Km). Thus the magnetic field at the flare kernels is of two kinds: one showing twist, shear, and possible compression, the other in the photospheric region near a sunspot group or a sunspot. The total energy of the flare is estimated to be about [FORMULA] erg.

Key words: Sun: activity — Sun: flare — Sun: magnetic fields


© European Southern Observatory (ESO) 1997

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