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A&A Supplement series, Vol. 129, May I 1998, 553-561

Received May 30, 1995; accepted September 4, 1997

Time evolution and morphological characteristics of white light flare on 18 January 1989

J.Y. Xuantex2html_wrap1439 - X.M. Gutex2html_wrap1441 - J. Lintex2html_wrap1439 - Y.C. Jiangtex2html_wrap1439 - S.H. Zhongtex2html_wrap1439 - Y.S. Litex2html_wrap1439

tex2html_wrap1451  CCAST (World Laboratory), P.O. Box 8730, Beijing 100080, China
tex2html_wrap1453  Yunnan Observatory, P.O. Box 110, Kunming 650011, China


Some properties of the white light flare (WLF) that occurred on 18 January 1989 are presented. The flare consisted of 7 patched-shape kernels, with sizes tex2html_wrap_inline1413 cm2. The lifetimes of the kernels were from several minutes to more than 40 minutes. The initial bright points of the WLF kernels originated between the umbra and penumbra, in penumbra fibrils, between penumbra fibrils and the photosphere, or on the photosphere and light bridge. These kernels appeared 2 to 3 minutes after Htex2html_wrap_inline1417 flares, and reached their maxima respectively before the first maximum and 1 to 2 minutes before the second maximum of the Htex2html_wrap_inline1417 flare, and disappeared slowly before the disappearance of the Htex2html_wrap_inline1417 flare. The direction and size of material motion in the kernels are different. The precursors of the WLF are similar to those of ordinary flares. The magnetic pattern of the photosphere in the active region is in tex2html_wrap_inline1423- structure, and the kernels lie at or near the changing magnetic neutral lines. The small longitudinal field gradient may be constrained by the small transverse field on the photosphere. The flare exhibited both temporal and spatial properties in the center reversal and line-width of Htex2html_wrap_inline1417 profiles, and has characteristics of both class I and II. Thus it may be a mixed-class white light flare.

keywords: sun: flares

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