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