(1) IZMIRAN, Troitsk, Moscow Region, Russia
(2) Solar Physics Research Corporation, ISAS,  Sagamihara, Japan

Introduction

Usually:

CHs are large-scale areas of relatively cool, low density and emission plasma with open, predominantly unipolar magnetic fields and without significant inside activity (e.g., Zirker, 1977;  K. Harvey, 1995; Mogilevsky et al., 1997; Obridko and Shelting, 1999; Zhao et al., 1999).

       Small-scale bright points (see Davis, 1985; Kahler and Moses, 1990; K.Harvey, 1995).
 

Sometimes --  medium-scale features in CHs:

• compact active regions (producing coronal jets)  (Shibata et al., 1994);
• emerging fluxes (e.g., Stepanian and Malanushenko, 2000).

• a sufficiently large filament located inside a big CH;
• disappearance/eruption of the filament accompanied by a number of large-scale dynamic phenomena (a coronal wave, chain, CME, arcade)

Yohkoh/SXT

H-alpha and Yohkoh/SXT

Data:

• SOHO/EIT (DelaboudiniХre et al., 1995) images and movies;
• Yohkoh/SXT (Tsuneta et al., 1991) images and movie;
• He I (10830 е) spectroheliograms of MLSO/HAO and Kitt Peak;
• H-alpha heliograms of MLSO, Mitaka, BBSO, Meudon, and KanSO;
• SOHO/LASCO (Brueckner et al., 1995) images and movies

                  SOHO/EIT,  Yohkoh/SXT -- negative (inverted) images;
                  He 10830 е,  H-alpha,  SOHO/LASCO -- positive (normal) images

On location of the filament

H-alpha and Yohkoh/SXT

        Comparison of the CH at He I, 10830 A with SOHO/EIT 284 A and Yohkoh/SXT images

        Open magnetic field lines on the synoptic map

        Open magnetic field lines and filament on the sphere

      Quasi-separatrix layers on the synoptic map

        Calculated magnetic data (combined; Figure 2)

Preceding activity

SOHO/EIT, 195 A (10-22 UT) (Figure 3)

  SOHO/EIT, 195 A (difference to 20:12 UT)

SOHO/EIT, 171 A (Figure 4)

MLSO/HAO, He I 10830 A

MLSO, H-alpha

Eruption

SOHO/EIT, 195 A (28d,22:36-29d, 01:48 UT (Figure 7)

 SOHO/EIT, 195 A (difference to 22:24 UT) (Figure 8)

  SOHO/EIT, 195 A (difference to 22:24 UT)

Yohkoh/SXT

MLSO and Mitaka H-alpha

Yohkoh/SXT

SOHO/EIT, 195 A

SOHO/EIT, 171 A
 

Accompanying activity

      SOHO/LASCO/C2 (Figure 9)

SOHO/LASCO/C2

SOHO/LASCO/C3

Yohkoh/SXT

SOHO/EIT, 171 A (Figure 4)

Dec 29, 1999 (Figure 10)

      SOHO/EIT, 195 A (09:12-18:24 UT) (Figure 3)

     SOHO/EIT, 171 A (Figure 4)

     MLSO/HAO H-alpha and He I 10830 A (Figure 5)

     SOHO/EIT, 195 A (difference to 22:24 UT) (Figure 8)
 

Conclusion

• This event is an example of a CH with a significant large-scale magnetic activity, including a disappearing filament and some other dynamic phenomena, internal to its boundaries.

• CHs may not be so simple and uniform structure as normally believed and can contain local areas with low-altitude, closed magnetic fields on large scales.

 
• The CH and erupted filament inside it interact with the adjacent active regions and are a part of a global evolving magnetic structure associated with activity extending almost throughout the whole east half of the disk.

 
• During all phases of the event, i.e. before, at the time of, and after the filament eruption, the large-scale bright chains of length comparable with the solar radius and even larger were observed particularly on the SOHO/EIT images at 171 and 195 A . Some clear chains illuminated the CH boundaries. One more meridional transequatorial chain crossed the CH, passed through the filament region and connected the remote north-east and south-east active regions, located nearby the CH, as well as another large, southern, eruptive filament.

 
• The present analysis encourages us in the assumption that at least some large-scale chains reveal the  QSLs of the 3D global solar magnetic fields. As shown in the analyzed event, the chains, located particularly along the CH boundaries, coincide closely with the computed QSLs.

 
• Similar (but not so spectacular) CH-interior activity appears to be presented in some other events.

 

   Compressed POSTSCRIPT file of the paper accepted at "Astrophys. J."

       paper_ps.zip  (3.3 MB)