ar091.yan01 Posted: 26-Apr-96 Updated: Events specified: See Text
by Yihua Yan (Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100080. TEL:86-10-2612194,FAX:86-10-2561085 EMAIL:YYH@bao01.bao.ac.cn) and (National Astronomical Observatory, Mitaka, Tokyo 181, Japan, Tel: 0422-343720, Fax:0422-343700, Email: yan@spot.mtk.nao.ac.jp)
Takashi Sakurai (National Astronomical Observatory, Mitaka, Tokyo 181, Japan, Tel: 81-422-343716, Fax:81-422-343700, Email: yan@spot.mtk.nao.ac.jp) and other collaborators are welcome.
MOTIVATION:
It is believed that solar magnetic fields dominate solar atmospheric activities. Coronal soft X-ray loops are in general believed to trace the local magnetic field lines and they should be expanded if the supporting field is potential. However, it has been noted for many years and showed recently by high-resolution observatoions (Klimchuk et al. 1992), that some coronal loops appear to have near-invariable thickness instead of being expanded. A recent study of thickness along coronal loops inferred from vector magnetogram data also indicates that highly sheared magnetic loops do not expand rapidly in height, but no comparison with X-ray data available (McClymont \& Mikic 1994). We will use a boundary element method (Yan 1995) to solve the force-free magnetic field and compare the computations with SXT observations, so as to investigate the associations between magnetic field lines and soft X-ray coronal loops.
DATA AND METHOD:
The Mitaka vector magnetograms by Flare Telescope are used as boundary conditions to extrapolating the 3-d magnetic structures above active regions. Then we wish to identify the correspondence between the magnetic topology and the simultaneously observed SXT data, and others when these are available.
EVENTS:
We have already found the simultaneous observation by different instruments for:
NOAA 7260 on 18 Aug, 1992 (at 2355UT by Mitaka, 2330UT-0030UT 19 Aug by SXT) NOAA 7123 on 16 Apr, 1992 (at 0522UT by Mitaka, 0318UT-0450UT by SXT) NOAA 7921 on 9 Nov, 1995 (at 2337UT by Mitaka, 2303UT by SXT)The effort to find more data set will be continued.