Observation of small scale reconnection role in undulated flux tube emergence

With Flare Genesis Experiment (FGE), a balloon borne observatory launched in Antarctica on January 2000, series of high spatial resolution vector magnetograms, Dopplergrams, and Hα filtergrams have been obtained in an emerging active region (AR 8844). We performed a linear force-free field extrapolation of the field above the photosphere. The analysis of the chromospheric magnetic topology reveals the existence of undulated low-lying field lines, presenting a 'sea-serpent' shape. These field lines are passing through several "Bald Patches" regions (BPs are regions where the vector magnetic field is tangential to the photosphere). These separatrice field lines are thus connected to the photosphere. The undulation spectrum leads us to suppose that the undulations are due to the Parker instability. In addition, these undulated field lines are highly associated with many shortlived and small-scale Hα brightenings called 'Ellerman bombs', which are likely to be due to magnetic reconnections along the BP separatrices. This observation permits us to conjecture that reconnection plays a key role in the flux tube emergence process. Arch filament systems and active region coronal loops do not result from the smooth emergence of large scale Ω loops, but rather from the rise of flat undulated flux tubes which get released from their photospheric anchorage by reconnection at BPs.