The active region (NOAA 5395) of 1989 March was a prolific flare-producing region. Some powerful flares were observed in this highly-sheared active region. We present the vector magnetic field observations of this region at the Huairou Solar Observing Station of the Beijing Astronomical Observatory. In this paper, the 180deg-ambiguity of the transverse magnetic field is resolved and the transformation of the observational vector magnetograms from the image plane to the heliographic plane is made. After reduction of the data obtained from this high-latitude active region, several results are obtained: 1) The twisted transverse magnetic field occurred in bay-like magnetic main poles of opposite polarity in the active region. The main poles of opposite polarity in this region moved apart at a speed of about 0.15km/s. 2) The newly-sheared vector magnetic structures formed near the magnetic neutral line between the collided magnetic main poles of opposite polarity. With the emergence of new magnetic flux, the change of sheared angles of the horizontal magnetic field between the magnetic main poles of opposite polarity is insignificant in comparison with daily vector magnetograms, but the distribution of the intensity of the vertical current inferred from the horizontal magnetic field evolved only gradually. 3) The flare sites occurred near the magnetic islands and bays of opposite polarity and were associated with the change of the vector magnetic field. Although some of the flare sites are located near the peak areas of the vertical electrical current density, their corresponding relationship is insignificant.
Astronomy and Astrophysics Supplement Series
- Pub Date:
- May 1995
- SUN: ACTIVITY;
- MAGNETIC FIELDS;