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C. Liu, N. Deng, J. Qiu, P. R. Goode, C. Denker, H. Wang (NJIT)
By tracing the change in TRACE white-light images, we find penumbral segments decayed rapidly and permanently right after three X-class solar flares. All of these three events occurred recently in NOAA Active Region 10486, an X17 flare on 2003 October 28, an X10 flare on 2003 October 29, and an X8.3 flare on 2003 November 2. For the X17 flare, the decaying penumbral segment is related to a section of one of the two TRACE 1600Å ribbons, while for the X10 and X8.3 flares, both to the 50-100 keV hard X-ray sources observed by RHESSI. We show the changes of photospheric magnetic fields associated with these penumbral decaying area by plotting the time profiles of magnetic flux derived from MDI magnetograms. We also use the TRACE 195Å images to understand the coronal environment. From all these observations, we propose a possible explanation that magnetic fields change from a highly inclined to a more vertical configuration after the flares, that is, part of the penumbral magnetic field is converted into umbral fields.
The author(s) of this abstract have provided an email address for comments about the abstract: CL45@NJIT.EDU
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Bulletin of the American Astronomical Society, 36 #2
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