1. Nobeyama, March, 2006
Collision of active regions visible in microwaves: 17 GHz Neutral Line Source as a “father” of weak and major flares some preliminary output of two week staying in NRO
Arkadiy Uralov, Victor Grechnev,
George Rudenko, Ilia Rudenko et al.
Institute of Solar-Terrestrial Physics
Irkutsk, Russia
Nobeyama Radio Observatory

2. This is the only established fact
Two kinds of quasi-stationary compact sources in 17 GHz emission of ARs
Sunspot associated – rather well understood
Neutral Line associated Sources – NLS
NLS certainly exist and show possible relation to some features and phenomena in ARs
This is the only established fact

3. Questions How do NLS appear and live? Do they have relation to flares?
To answer these questions, we study evolution of an appropriate AR
The target is AR during the active period of October/November 2003

4. AR 488 shows an impressive chain of events
begin
birth of two active regions 
their collision 
NLS appears 
small flares in NLS 
major flare starts in NLS 
major flare develops 
NLS reappears
end

5. October - November 2003 SSRT,  = 5.2 cm, intensity
2003/10/27 02:41 UT
487
488
486
484
487
488
486
484
SOHO/MDI 6767 Å continuum
2003/10/26 22:24 UT
NoRH,  = 1.7 cm, intensity
2003/10/27 02:40 UT

6. Birth and collision of two ARs
Oct. 27
Oct. 28
Oct. 29
Oct. 30
Oct. 31
Nov. 01
AR 488
17 hours after birth
new AR birth
collision of AR’s
NLS
MDI magnetograms of AR 10488: red – N, blue – S

7. Birth of a Neutral Line Source
I17 color
Br contours
Bt color
Br contours
October~30
October~31
November~1
I color
|B| contours

8. Small flares and NLS: most 17 GHz bursts occur in the NLS

9. 17 & 34 GHz flare starts in the NLS
X2.7 flare and NLS
NLS
sunspot
17 & 34 GHz flare starts in the NLS

10. Summary-I
AR 10488
Collision of two bipolar ARs leads to formation of a quadrupole magnetic structure, which contains an X-point. Its probable location is above the closest contact of dipoles visible in magnetograms.
At this place, NLS at 17 GHz appears and persists. For the first time, we have shown evidence for that.
NLS is noisy. Its noise is a series of small bursts. This noise probably reflects the noise of a current sheet.

11. Summary-II
AR 10488
The current sheet exists well before major flares. There is no need to create it for the initiation of a flare (which was a problem of some CME+flare models).
The magnetic structure, corresponding to the NLS, was probably located close to the bottom of the current sheet. This is why the major flare started just in the NLS. The presented movie evidences for a connection between 17GHz NLS and major flares.

12. We acknowledge
Shibasaki San and NSRO for the opportunity to work here under perfect conditions
Staff members of the NSRO for the hospitality
The Fortune for the luck to unexpectedly find what we anticipated