2 April 1999
- The Nobeyama Radioheliograph data show that in the microwave range,
besides large-scale trans-equatorial chains (see, e.g., the May
11-15, 1993 and November 1-4, 1993 events),
there are also many examples displaying large and strongly evolving
or "internal" chains connecting remote active regions inside
an active zone in one (northern or southern) hemisphere (the August
20-September 3, 1998 event).
- A consideration of the Nobeyama Radioheliograph data from June 1992
to March 1999 bring one to the following preliminary conclusion about the
long-living microwave chains at the different stage of the solar activity
cycle: at the decreasing phase of the 22nd cycle many trans-equatorial
chains were observed (the May 11-15, 1993 and
November 1-4, 1993 events), while at the
present increasing phase of the 23rd cycle the "longitudinal"
or "internal" chains are mainly characteristic (the August
20-September 3, 1998 event). This feature appears to be due to the
corresponding low-latitude and high-latitude locations of the active zones.
- Simultaneous observations in the EUV range with the SOHO/EIT and
TRACE, available now, allow to compare the images received with these
two space observatories at the same wavelengths. Such a comparison shows
that the quite identical chains and threads are present on the corresponding
modified SOHO/EIT and TRACE images (the October 13,
1998 and March 30, 1999 events). It is the
most direct proof of the reality of this novel phenomenon of the
large-scale solar activity.
- The large-scale chains and threads observed in different ranges provide
additional evidences that various remote active regions and other structures
are closely related between themselves and form an unified, complex
and global solar magnetosphere like to that as several
sunspots form the active region magnetosphere.
- It is highly probable that the large-scale chains, particularly in
the EUV range, light separators and quasi-separatrix layers forming
on the boundaries of different interacting large-scale magnetic flux systems
in the global solar magnetosphere.
- The fact that large-scale chains appear to reveal a close association
with CMEs is a consequence that both these phenomena results from the evolution
of the global solar magnetosphere and some its structures and that the evolving
large-scale chains and threads appear to be an indicator of the development
of the corresponding structures of the global solar magnetosphere (see,
e.g., the March 28-April 02, 1999 event).
- A spectacular evolution of the chains and threads appears to occur
not only after a CME (the August 22-23, 1996
event) at the stage of the prolonged post-CME energy release, but
also before that (the June 1-2, 1998 event),
when large-scale magnetic structures approach to their unstable state.
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Last update: 2 April 1999