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The Recovery of CME-Related Dimmings and the ICME’s Enduring Magnetic Connection to the Sun 总被引:1,自引:1,他引:0
G. D. R. Attrill L. van Driel-Gesztelyi P. Démoulin A. N. Zhukov K. Steed L. K. Harra C. H. Mandrini J. Linker 《Solar physics》2008,252(2):349-372
It is generally accepted that transient coronal holes (TCHs, dimmings) correspond to the magnetic footpoints of CMEs that
remain rooted in the Sun as the CME expands out into the interplanetary space. However, the observation that the average intensity
of the 12 May 1997 dimmings recover to their pre-eruption intensity in SOHO/EIT data within 48 hours, whilst suprathermal
unidirectional electron heat fluxes are observed at 1 AU in the related ICME more than 70 hours after the eruption, leads
us to question why and how the dimmings disappear whilst the magnetic connectivity is maintained. We also examine two other
CME-related dimming events: 13 May 2005 and 6 July 2006. We study the morphology of the dimmings and how they recover. We
find that, far from exhibiting a uniform intensity, dimmings observed in SOHO/EIT data have a deep central core and a more
shallow extended dimming area. The dimmings recover not only by shrinking of their outer boundaries but also by internal brightenings.
We quantitatively demonstrate that the model developed by Fisk and Schwadron (Astrophys. J.
560, 425, 2001) of interchange reconnections between “open” magnetic field and small coronal loops is a strong candidate for the mechanism
facilitating the recovery of the dimmings. This process disperses the concentration of “open” magnetic field (forming the
dimming) out into the surrounding quiet Sun, thus recovering the intensity of the dimmings whilst still maintaining the magnetic
connectivity to the Sun.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献