The Filament Eruption of 1999 March 21 and Its Associated Coronal Dimmings and CME

Abstract

We report a filament eruption near the center of the solar disk on 1999 March 21, in multi-wavelength observations by the Yohkoh Soft X-Ray Telescope (SXT), the Extreme-ultraviolet Images Telescope (EIT) and the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The eruption involved in the disappearance of an H alpha filament can be clearly identified in EIT 195 angstrom difference images. Two flare-like EUV ribbons and two obvious coronal dimming regions were formed. The two dimming regions had a similar appearance in lines formed in temperature range 6 x 10(4) K to several 10(6) K. They were located in regions of opposite magnetic polarities near the two ends of the eruptive filament. No significant X-ray or H alpha flare was recorded associated with the eruption and no obvious photospheric magnetic activity was detected around the eruptive region, and particularly below the coronal dimming regions. The above surface activities were closely associated with a partial halo-type coronal mass ejection (CME) observed by the Large Angle and Spectrometric Coronagraphs (LASCO) on the SOHO. In terms of the magnetic flux rope model of CMEs, we explained these multiple observations as an integral process of large-scale rearrangement of coronal magnetic field initiated by the filament eruption, in which the dimming regions marked the evacuated feet of the flux rope.