Evolution of Filament Barbs

We present a selected few cases in which the sense of chirality of filament barbs changed within as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes only one overlay a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward and then departed from each other in H-alpha, with the barb endpoints migrating as far as ~10". We conclude that the evolution of the barbs was driven by flux emergence and cancellation of small bipolar units at the EFC border.