Filament activity and photospheric magnetic evolution related to flares

¹ Beijing Astronomical Observatory, National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, PR China
² Yunnan Astronomical Observatory, Chinese Academy of Science, Kunming 650011, PR China e-mail: jych@ourstar.bao.ac.cn

Corresponding author: Y. Jiang, jyc@cosmos.ynao.ac.cn

Received: 20 March 2000
Accepted: 25 August 2000

Abstract

Three successive activations of an active-region filament were observed over a period of eight hours. Each disturbance showed distinctive characteristics and was followed by a flare of different properties. The filament had one end rooted in strong -sunspots. During the first activation, the filament rose up at the rooting end and detached from the -sunspots while its main body remained in place and separated into two twisted threads. During the second activation, only one thread was disturbed and finally disappeared; twisted threads, however, appeared during the third activation. The evolution of photospheric magnetic fields, associated with the filament disturbances, was characterized by squeezing and shearing of -sunspots, flux cancellation and emergence beneath the two ends of the filaments. Our data suggests that magnetic reconnection in the photospheric layer is the likely cause of filament destabilisation.