High Resolution Observations of Reconnected Magnetic Loops

LUONI, M.L.; MANDRINI, C.H.; KARIM, Y.; SCHMIEDER, B.; DÉMOULIN, P.

Córdoba

Congreso; X IAU Reunion Regional Latinoamericana de Astronomia; 2001

IAU

In this work we find observational evidence of magnetic reconnection in a are that occurred on 15 October, 1999. We concentrate our study in the evolution of bright coronal loops appearing at are onset. Active region (AR) NOAA 8731 was observed by SoHO and TRACE satellites and ground-bases observatories (Wroclaw Obs., Poland). MDI/SoHO longitudinal magnetograms give us the opportunity to model the magnetic eld. We extrapolate the photospheric longitudinal magnetic field to the corona under the linear force-free assumption taking different values of the parameter alpha, which are determined to best fit the coronal loops observed with TRACE. Computing the magnetic topology of the AR, we find the presence of \quasi{separatrix layers" (QSLs) and \bald patches" (BPs). QSLs appeared related to a new emerging bipole and the main active region polarities. Interaction between loops belonging to these ux concentrations at QSLs originate the former are kernels. Loops where energy is deposited after reconnection are seen bright in TRACE images at 12:43 UT. A second set of loops is observed to brighten a few minutes after. These loops are associated with BPs. We conclude that these observations represent a direct evidence of magnetic reconnection at QSLs during ares, and that this former energy release modies the global magnetic conguration inducing a second release at BPs and their associated separatrices.