Contraction of flaring loops — the evidence of magnetic reconnection in sheared core fields

Haisheng JiPurple Mountain ObservatoryNanjing, 210008, Chinajihs@pmo.ac.cn

What is the Contraction of flaring loops?

That is, during the rising phase of solar flares, hard X-ray (HXR) loop-top sources or radio/extreme-ultraviolet (EUV) flaring loops have a descending motion and, at the same time, Hα ribbons or HXR footpoints (FPs) are converging. The usual expansion motion (upward motion + separation motion) of flaring loops occurs only after the contraction. 

Unshearing occurs during the contraction as well as the expansion motion.

Dynamic flaring loops— A Summary from our observations

• 中国古代天文学家对太阳黑子的描述，大体可分为三大类：• 第一类，圆形：如钱、如桃、如李、如栗、如环。• 第二类，椭圆形：如鸡卵、鸭卵、鹅卵、爪、枣。• 第三类，不规则形：如立人、如踆乌、如飞鹊、如飞燕。

• 《淮南子•精神训》载：“日中有踆乌，而月中有蟾蜍。”东汉高诱注云：“踆，犹‘蹲’也，谓三足乌。”晋代学者郭璞（ 276 ～ 324 ）也有注释说“中有三足乌”。

Events showing the contraction

• The M1.2 flare of 2002-04-15 (Sui & Holman 2003)• The M2.1 flare of 2002-09-09 (Ji et al. 2004)• The X3.1 flare of 2002-08-24 (Li & Gan 2005)• The X3.9 flare of 2003-11-03 (Veronig et al. 2006)• The M1.2 flare of 2004-11-01 (Ji et al. 2006)• The M6.8 flare of 2003-06-13 (Ji, Huang, & Wang 2007)• The M5.7 flare of 2002-03-14 (Zhou, Ji & Huang 2006)• The X10 flare of 2003-10-29 (Zhou, Ji & Huang 2006; Ji et al. 2008)

in the early phase of the flares, the looptop sources moves down

Velocity ~ tens of kilometers per second

10-25 keV

The M1.2 flare of 2002-04-15(Sui and Holman 2003)

the first SMESE workshop 10-12 March 2008, Paris

The X3.1 flare of 2002-08-24

(Li and Gan 2005)

the first SMESE workshop 10-12 March 2008, Paris

The M3.9 flare of 2003-11-03

(Veronig et al. 2006)

the first SMESE workshop 10-12 March 2008, Paris

The M2.1 flare of 2002-09-09 (Ji et al. 2004)

Red: 6-12keVBlue: 12-25kev

25-50 keV

25 km/s

17:41 UT

17:46UT

The M1.2 flare of 2004-11-01: (Ji et al. 2006)

03:18:44 – 03:18:56

03:19:08 – 03:19:20 Solid: 25-60 keVDashed: 6-10 keV

the first SMESE workshop 10-12 March 2008, Paris

The M6.8 flare of 2003-06-17 (Ji et al. 2007)

The flare of 2002-03-14(Zhou et al. 2007)

Background: TRACE 171 AContours: HXR 30-60 keV

the first SMESE workshop 10-12 March 2008, Paris

• White-light flare (Xu et al. 2004)

• Penumbral decay and rapid magnetic changes (Wang et al. 2004)

• Gamma-ray (Hurford et al. 2006)

• Large scale disturbance (Liu et al. 2006; Balasubramaniam, Pevtsov \& Neidig 2007)

• Shear flows (Deng et al. 2006)

• Magnetic unshearing after flare (Wang et al. )

• Significant helicity drop after flare (Liu et al. 2007)

• Significant geophysical effect (Kwabara et al. 2004)

• Contraction-to-expansion (Zhou et al. 2007)

The X10 flare of 2003-10-29 (Ji et al. 2008)

10-25 keV 35-50 keV

The X10 flare of 2003-10-29 (Ji et al. 2008)

the first SMESE workshop 10-12 March 2008, Paris

The X10 flare of 2003-10-29

Sigmoid arcade

the first SMESE workshop 10-12 March 2008, Paris

The X10 flare of 2003-10-29 (Ji et al. 2008)

the first SMESE workshop 10-12 March 2008, Paris

Sigmoid phase

Arcade phase

The X10 flare of 2003-10-29 (Ji et al. 2008)

The X10 flare of 2003-10-29 (Ji et al. 2008)

the first SMESE workshop 10-12 March 2008, Paris

Contraction expansion

The X10 flare of 2003-10-29 (Ji et al. 2008)

the first SMESE workshop 10-12 March 2008, Paris

• Sigmoidal structure first ever seen in HXR• Magnetic reconnection inside the sigmoid• Sigmoid arcade • Contraction expansion • Unshearing throughout the flare• Rapid unshearing during the ‘sigmoid’ period

The X10 flare of 2003-10-29 (Ji et al. 2008)

the first SMESE workshop 10-12 March 2008, Paris

the first SMESE workshop 10-12 March 2008, Paris

Contraction of flaring loops ☆ inward motion of conjugate flaring kernels

☆ shrinkage of flaring loops (radio, EUV) ☆ descending of HXR looptop sources

Expansion of flaring loops

☆ outward motion of conjugate flare ribbons ☆ expansion of flare loops (radio, EUV)

☆ upward motion of HXR looptop sources

the first SMESE workshop 10-12 March 2008, Paris

dynamic flare loops

A B C D

E F Gthe first SMESE workshop

10-12 March 2008, Paris

dynamic flare loops

the first SMESE workshop 10-12 March 2008, Paris

Interpretation of Loop Contraction10-25 keV

1. Current sheet formation (Sui & Holman 2003, Sui et al. 2004)

2. Magnetic shrinkage (Acton & Forbes1996,

Lin 2004)

3. Collapsing magnetic trap (Veronig et al. 2005)

4. Magnetic Implosion (Hudson 2000)

V dVB )8/( 2 reducedthe first SMESE workshop

10-12 March 2008, Paris

V dVB )8/( 2

Mapping effectfrom

the Photosphere

Modifying effect caused by

Our interpretation (Ji et al. 2007)

the first SMESE workshop 10-12 March 2008, Paris

Our interpretation (Ji et al. 2007)

• Contraction is the signature of magnetic energy dissipation in highly sheared magnetic field

Energy dissipation

the first SMESE workshop 10-12 March 2008, Paris

The implication for the relationship of flares and CMEs

sigmoidal phase arcade phase

contraction expansion+

+

CMEs

the first SMESE workshop 10-12 March 2008, Paris

THANK YOU!

the first SMESE workshop 10-12 March 2008, Paris