Observations of magnetic field reconnection at the base of EFR surges
H. kurokawa, Y. Liu, S. Sano, and J. Kiyohara
We found conspicuous Halpha surge activities at the earliest stage
of some active regions and suggested that the Halpha surge is one of the
first manifestations of the active region birth (Kurokawa 1988). We
call such Halpha surges as EFR surges.
>From the morphological studies of EFR-surges, we presented a schematic
model of surge production where the surge is produced by the
reconnection between the emerging magnetic flux and the pre-existing
surrounding magnetic field of opposite magnetic polarity (Kurokawa and
Kwai 1993). Yokoyama and Shibata (1996) succeeded to reproduce it by
their numerical simulation.
As for the magnetic field of surge region, we found longitudinal
magnetic field flux of an isolated polarity increased at the bases of
most surges during and after the surge activities (Sano and Kurokawa
2005). We also found magnetic field cancellation between one polarity
of emerging flux and the surrounding opposite polarity at the surge base
(Yoshimura et al. 2003, Brooks and Kurokawa 2005). Those observational
evidences are all compatible with the reconnection model of the EFR surge.
We will challenge to find the first clear evidences of changes
in transverse magnetic field at the base of the EFR surges to give
proof of the magnetic field reconection with the vector
magnetograph of the SOT.
Correspondence
Hiroki Kurokawa (kurokawa@kwasan.kyoto-u.ac.jp), Kwasan & Hida Observatories ,Graduate School of Science, Kyoto
University
presentation
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