RAPID CHANGES OF SUNSPOT STRUCTURE ASSOCIATED WITH SEVEN

MAJOR FLARES

C. Liu, N. Deng, J. Qiu, Y. Liu†, D. Falconer,P. R. Goode, C. Denker, H. Wang

Center for Solar-Terrestrial Research, NJIT†Kwasan and Hida Observatories, Kyoto University

Short report at Kwasan and Hida Obs. 2004/11/01

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ABSTRACT

By studying the change in TRACE white-light images, we find penumbral segments decayed rapidly and permanently right after seven major flares. Meanwhile, we observe central region (umbra/penumbra) enhancement near the magnetic neutral lines.

The locus of penumbral decay is related to flare emission, either RHESSI HXR kernels or TRACE ribbon. MDI magnetogram and TRACE 195/171Å data are used to study the change of photospheric magnetic fields and coronal environment.

We propose a possible explanation that magnetic fields change from a highly inclined to a more vertical configuration after the flares.

We present more events exhibiting penumbra decay and we speculate that, this might be a universal phenomena associated with δ-sunspots.

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Date

Start (UT)

Peak(UT)

AR

Number Size

Location

(deg)

10/28/03 09:51 11:10 0486 X17. S18E20

10/29/03 20:37 20:49 0486 X10. S15W02

11/02/03 17:03 17:25 0486 X8.3 S14W56

06/06/00 14:58 15:25 9026 X2.3 N33E25

04/06/01 19:10 19:21 9415 X5.6 S20E31

04/09/01 15:20 15:34 9415 M7.9 S21W04

08/25/01 16:23 16:45 9591 X5.3 S17E34

Penumbra Decaying Events

All these flares are originated from δ-sunspots

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X10 flareon 10/29/03

D1 & D2:penumbra decaying areas, both associated with HXR kernels

E1:central darkening area

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Mean intensity increase indicates feature decaying; intensity decrease indicates darkening.

After the X10 flare, intensities change rapidly and permanently. The associated photospheric longitudinal magnetic fields also exhibit rapid changes closely related to the flare.

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MEES/IVMWL, BZ, AND BT MAPS

It shows more clearly that the transverse fields associated with the two penumbra decaying areas (D1&D2) dropped after the flare, while enhanced at the central darkening region (E1).

D1 D2

E1

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MSFC WL, Bz, AND Bt MAPS

D1: -256G D2: -74G E: +196G

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TRACE 195Å IMAGES

By comparing the change shown in the coronal images, it is obvious that new strong loops formed within the δ-sunspot region (red box) after the flare due to the magnetic reconnection.

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X17 FLARE ON 10/28/03D5 & D6: penumbra decaying areas, both associated with trace 1600å ribbons E3: central darkening area

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TRACE 195Å IMAGES

SUNSPOTS NOT

CONNECTED

CONNECTED

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X8.3 FLARE ON 11/02/03

D3 & D4:Penumbra decaying areas, both associated with HXR kernels

E2:central darkening area

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TRACE 195Å IMAGES

SUNSPOTS NOT

CONNECTED

CONNECTED

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MORE EVENTS #1:08/25/01 16:45 UT X5.3 FLARE

D1: -20G

D2: -36G

E: +113G

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MORE EVENTS #2:04/06/01 19:21 UT X5.6 FLARE

D1

D2E

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MORE EVENTS #3:04/09/01 15:34 UT M7.9 FLARE

D1

D2

E

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MORE EVENTS #4:06/06/00 15:25 UT X2.3 FLARE

D2

D1

E

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SUMMARY1. All the events shown are two-ribbon flares and are associated

with cmes2. Two or more penumbra decaying areas are found which lie in

the outer δ-sunspot structure3. The central sunspot region (umbra or penumbra area) become

darkened after the flare (DBD mode; D-dark, B-bright)

4. The two sunspots which constitute the δ-sunspot become connected after the flare

5. The observed intensity changes are permanent, not transient6. The locus of penumbra decay is related to flare emission

We propose a simple reconnection model for δ-sunspot which can explain both the penumbra decay and central area darkening

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Possible reconnection scenario of δ-sunspot

The penumbra fields change from a highly inclined to a more vertical configuration after the flare, and the two sunspots become

connected

penumbra decays and center darkens

umbral fields

penumbral fields