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
Nobeyama, 15-16 March, 2006
Two kinds of quasi-stationary compact sources in 17 GHz emission of ARs
1. Sunspot associated – rather well understood
2. 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
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 10488 during the active period of October/November 2003
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
NoRH, = 1.7 cm, intensity2003/10/27 02:40 UT
SOHO/MDI 6767 Å continuum2003/10/26 22:24 UT
487488
486
484
SSRT, = 5.2 cm, intensity2003/10/27 02:41 UT
487488
486
484
October - November 2003
Birth and collision of two ARsOct. 27 Oct. 27 Oct. 28 Oct. 29
Oct. 29 Oct. 30 Oct. 31 Nov. 01
new AR birth collision of AR’s AR 488 17 hours after birth
MDI magnetograms of AR 10488: red – N, blue – S
NLS
I17 color
Br contours
October~30 October~31 November~1I17 color
|B| contours
Bt color
Br contours
Birth of a Neutral Line Source
Small flares and NLS: most 17 GHz bursts occur in the NLS
X2.7 flare and NLS
NLS
sunspot
17 & 34 GHz flare starts in the NLS
Summary-I
• 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.
AR 10488
Summary-II
• 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.
AR 10488
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