A solar eruption driven by rapid sunspot rotation

Guiping Ruan, Yao Chen, Shuo Wang, Hongqi Zhang, Gang Li, Ju Jing, Xing Li, Haiqing Xu, and Haimin Wang

2013.10.31

Contents

IntroductionObservations and data reductionResults and summary

2013.10.31

IntroductionSunspot rotation was first observed a century ago by

Evershed (1910) which has been considered to be an important process (e.g., Stenflo 1969; Barnes & Sturrock 1972; Amari et al. 1996; Tokman & Bellan 2002; Török & Kliem 2003)

Previous studies revealed some temporal and spatial association of sunspot rotation with solar flares (Brown et al. 2003;Regnier et al. 2006; Yan et al. 2007, 2008a, 2008b, 2009; Zhang, Li & Song 2007; Zhang,Liu & Zhang 2008; Jiang et al. 2012,

Vemareddy et al. 2012): focusing on flares, yet not VERY strong, especially, the asso. to CMEs has not been well-examined.

Based on the MHD flux rope modeling ,Török et al. (2013) assumed that the CME on 6 July 2006 from AR10898 was triggered by the weakening and expansion of the overlying coronal fields caused by sunspot rotation, yet lack of observational support/evidence. 2013.10.31

The flare-CME-filament eruption on Sept. 6 2011 (AR 11283), well observed by SDO/STEREO!

X2.1 FLARE (peaking: 22:20)CME: 1200 km/sWhat process/mechanism driving this MAJOR eruption?

First, examine the sunspot evolution in ~12 hs pre-eruptionApparent sunspot rotation in ~6 hs before the eruption!

Put the sunspot rotation and filament eruption togetherDuring the 6h rotation, the filament rises gradually and erupts eventually !

Left: angular-time plot

Right: Height-time plot

The filament is rooted in the rotating sunspot!

Contours: Bz=±350 G

Previous slides show direct evidences supporting the association of the filament eruption and the sunspot rotation, now we present other indirect evidences!

1. Gradual decrease of Bh during the sunspot rotation;

2. Gradual decrease of B_inclination angle (tan−1 (Bx2 + By2 )1/2/Bz);

3. Gradual levitation of the coronal current density map as inferred from the NLFFF modeling.

1. Change of Bh (the horizontal magnetic field).Pre- and post- flare JUMP (Wang et al.,

1994,2010,2012).We examine the Bh evolution in the region of

interest.

Bh: a gradual decrease during the sunspot rotation

B_inclination angle: a gradual decrease

Red line: Start of sunspot rotation

Gradual levitation of the coronal current densitymap as inferred from the NLFFF model

(Wiegelmanne,04)

Previous slides show direct evidences supporting the association of the filament eruption and the sunspot rotation, now we present other indirect evidences!

1. Gradual decrease of Bh during the sunspot rotation

2. Gradual decrease of B_inclination angle3. Gradual levitation of the coronal current

density map as inferred from the NLFFF modeling Putting them together

with a flux rope model: Gradual levitation of the flux ropeB gets more vertical, inclination angle smaller, the whole current structure moves higher!

Indeed, we find flux rope structure with the NLFFF model!

And, significant free energy stored in the corona during the sunspot rotation (~30% of the total free energy released by the eruption)!

Start of sunspot rotation

End of flare

=

Along with the sunspot rotation, significant amounts of magnetic energy (~1031erg) and helicity (~1041 Mx2) were transported into the corona.

△H=3.5x1041Mx2

(LCT method, Chae et al. 2001)

Start of sunspot rotation

ConclusionWe find direct evidences connecting the CME-flare-filament

eruption to the sunspot rotation:

(1) corresponding dynamical motion of the filament along with the rotation

(2) the filament is rooted in the rotating sunspot

Also, indirect evidences including:

1. Gradual decrease of Bh during the sunspot rotation

2. Gradual decrease of B_inclination angle3. Gradual levitation of the coronal current

density map as inferred from the NLFFF modeling

All these aspects of observations can be explained with a flux-

rope eruption model driven by sunspot rotation!

Thanks !