Direct observation of the energy release site in a solar flare by SDO/AIA, Hinode/EIS and RHESSI Paulo J. A. Simões1, David R. Graham1,2, Lyndsay Fletcher1!

1- SUPA School of Physics and Astronomy, University of Glasgow, UK!2- INAF – Osservatorio Astrofisico di Arcetri, Italy!

2. Observational Results !This flare was characterised by two ribbons5 and a compact, bright coronal source, which is the focus of our analysis.!!•  Impulsive EUV emission observed in all AIA

channels (94, 131, 171, 193, 211, 304, 1600 and 1700 Å), see Fig. 1.!

•  Strong red-shifts in EUV spectral lines formed at a range of temperatures, 5.4 < log T < 7.2, indicating fast flows of 40-250 km/s. See Fig. 2 and Fig. 4. !

•  Hard X-ray (HXR) images and spectra from RHESSI indicate both thermal and non-thermal emission at the coronal source. See Fig. 3.!

•  The high density plasma (3x1011 cm-3, Fe XIV line pair diagnostic) in the region is collisionally thick to electrons up to 65 keV, explaining the high-energy HXR emission at the coronal source6 (see Fig. 3b).!

•  Outflows of ~150 km/s from the coronal source towards the ribbons observed in AIA images at 171, 193, 211, 304 and 1600 Å. See Fig. 5.!

•  Separation of loops are seen in AIA images, suggesting reconnection between crossing loops7,8,9 (see Fig. 6).!

References!![1] Su et al. 2013 Nature Phys. 9, [2] Wang, Sui, Qiu 2007 ApJ 661, [3] Hara et al. 2011 ApJ 741, [4] Brosius 2012 ApJ 754, [5] Simões, Graham, Fletcher 2015 Sol.Phys. Accepted, [6] Wheatland & Melrose 1995 Sol.Phys. 158, [7] Chae 1999 J. Korean Astron. Soc. 32, [8] Melrose 1997 ApJ 486, [9] Melrose 2004 Sol. Phys. 221.!

1. Introduction !We present direct evidence of the detection of the main energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38 UT, observed by the Hinode/Extreme ultraviolet Imaging Spectrometer (EIS), Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). !!The release of magnetic energy causes plasma heating and particle acceleration, sometimes with clear evidence of a fast re-organisation of the magnetic structure1. Plasma flows (observed as red- or blue-shifted emission lines) are also expected near the energy release2,3,4 (e.g. magnetic reconnection) sites. All these processes were observed in this event.!

Paulo.Simoes@glasgow.ac.uk!

The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 606862 (F-CHROMA); !STFC ST/I001808/1 and ST/L000741/; STFC “STEP”!

Online material !Watch the AIA movie!Download the poster!Read the paper !!bit.ly/1Csfjm8 !!or scan the QR code!

3. Interpretation !Our interpretation of the flare is as follows: component magnetic reconnection between crossing, current-carrying loops (consistent with observed geometry and loop motion, Fig. 6) releases energy into a dense loop, heating the local plasma and accelerating particles (Fig. 1, 2 and 3). The high temperature enhances the local pressure driving plasma flows (at the ion-sound speed) towards the ribbons. These flows are observed as red-shifted components in all observed EUV lines by EIS (Fig. 4) and bright moving structures in AIA images (Fig. 5). The high temperature plasma at the site cools rapidly by conduction, in about one minute (Fig. 3b).!

Fig. 2 Hinode/EIS velocity maps of the red-shifted right component of Fe XII 192.4 Å!

Fig. 4 Fitted EIS spectra for 3 raster positions across the coronal source. The emission lines exhibit a clear red-shifted component – the rest wavelengths are indicated by the vertical lines, see details in each panel.!

Fig. 6 a) AIA image to represent the pre- and post-reconnection field lines; b) time-slice diagram along the cut shown in (a) and estimates of the retraction speed of the reconnected field. !

Fig. 1 SDO/AIA 94 Å image of the flaring region, overlaid with 1600 Å contours. The main flare sources are identified: coronal source, East and West ribbons.!

Fig. 5 a) Composite of AIA images at different times, showing the flow along the loops (indicated by the arrow) b) time-slice diagram along the arrow shown in (a) and estimates of the flow speed. The onset of the flows are well associated with HXR bursts (red curve).!

Fig. 3 a) RHESSI hard X-ray sources (contours, see details in the panel) overlying an AIA 171 Å image. b) Plasma temperature evolution derived from HXR data, indicating fast heating and cooling at the coronal source.!

O V 248.480

248.3 248.4 248.5 248.6 248.7Wavelength (Å)

0

2

4

6

8

x103 e

rgs

cm−2

s−1

sr−1

Å−1

log T = 5.4

06:26:02

O V 248.480

248.3 248.4 248.5 248.6 248.7Wavelength (Å)

0

2

4

6

8

10

12

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 120±11 km s−1

log T = 5.4

06:26:13

O V 248.480

248.3 248.4 248.5 248.6 248.7Wavelength (Å)

0

2

4

6

8

10

12

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 85±24 km s−1

log T = 5.4

06:26:24

Fe XII 195.120

194.8 194.9 195.0 195.1 195.2 195.3 195.4Wavelength (Å)

0

10

20

30

40

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = −6±4 km s−1

Vel2 = 218±7 km s−1

log T = 6.2

06:26:02

Fe XII 195.120

194.8 194.9 195.0 195.1 195.2 195.3 195.4Wavelength (Å)

0

20

40

60

80

100

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 72±35 km s−1

Vel2 = 135±89 km s−1

log T = 6.2

06:26:13

Fe XII 195.120

194.8 194.9 195.0 195.1 195.2 195.3 195.4Wavelength (Å)

0

10

20

30

40

50

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 53±3 km s−1

Vel2 = 190±36 km s−1

log T = 6.2

06:26:24

Fe XIV 274.200

274.0 274.1 274.2 274.3 274.4Wavelength (Å)

0

2

4

6

8

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 2±4 km s−1

log T = 6.3

06:26:02

Fe XIV 274.200

274.0 274.1 274.2 274.3 274.4Wavelength (Å)

0

2

4

6

8

10

12

14

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 22±3 km s−1

log T = 6.3

06:26:13

Fe XIV 274.200

274.0 274.1 274.2 274.3 274.4Wavelength (Å)

0

2

4

6

8

10

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 31±4 km s−1

log T = 6.3

06:26:24

Fe XVI 262.980

262.7 262.8 262.9 263.0 263.1 263.2 263.3Wavelength (Å)

−2

0

2

4

6

8

10

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 3±3 km s−1

Vel2 = 228±23 km s−1

log T = 6.8

06:26:02

Fe XVI 262.980

262.7 262.8 262.9 263.0 263.1 263.2 263.3Wavelength (Å)

0

2

4

6

8

10

12

14

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 32±6 km s−1

Vel2 = 169±8 km s−1

log T = 6.8

06:26:13

Fe XVI 262.980

262.7 262.8 262.9 263.0 263.1 263.2 263.3Wavelength (Å)

0

2

4

6

8

10

12

x103 e

rgs

cm−2

s−1

sr−1

Å−1

Vel1 = 44±6 km s−1

Vel2 = 185±14 km s−1

log T = 6.8

06:26:24

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

AIA 94 Å 06:25:49.120AIA 1600 Å 06:25:52.120

Coronal source

East ribbon

West ribbon

a)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

06:26:14.79006:26:47.63006:27:35.620

06:26:14.79006:26:47.63006:27:35.620

Flows

b)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

AIA 171 Å 06:25:49.430RHESSI 4.1−4.9 keV 06:25:31+20.0sRHESSI 12.8−15.0 keV 06:25:31+20.0sRHESSI 23.0−27.6 keV 06:23:34+308.8s

c)

0 20 40 60 80 100 120X (arcsecs)

PIL

−400

−200

0

200

400

LOS

mag

netic

fiel

d [G

]

HMI 06:30:27.900AIA 1600 Å 06:25:52.120HMI 06:30:27.900AIA 1600 Å 06:25:52.120

d)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

−300

−200

−100

0

100

200

300

Velo

city

[km

s−1

]

a) Fe XII 192.394 Å (right)

06:2

6:24

.045

(a)

06:2

6:13

.447

(b)

06:2

6:02

.857

(c)

0 20 40 60 80 100 120X (arcsecs)

b) Fe XXIV 192.028 Å (right)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

06:28:16.12006:27:28.12006:26:16.120

06:28:16.12006:27:28.12006:26:16.120

Flow

c)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

d)

v1=149 km s−1

v2=76 km s−1

RHESSI 12−25 keV

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

CUT ++

−

−v=14.8 km s−1

v=13.7 km s−1

after reconnectionbefore reconnection

e)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

v=14.8 km s−1

v=13.7 km s−1

f)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

−300

−200

−100

0

100

200

300

Velo

city

[km

s−1

]

a) Fe XII 192.394 Å (right)

06:2

6:24

.045

(a)

06:2

6:13

.447

(b)

06:2

6:02

.857

(c)

0 20 40 60 80 100 120X (arcsecs)

b) Fe XXIV 192.028 Å (right)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

06:28:16.12006:27:28.12006:26:16.120

06:28:16.12006:27:28.12006:26:16.120

Flow

c)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

d)

v1=149 km s−1

v2=76 km s−1

RHESSI 12−25 keV

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

CUT ++

−

−v=14.8 km s−1

v=13.7 km s−1

after reconnectionbefore reconnection

e)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

v=14.8 km s−1

v=13.7 km s−1

f)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

−300

−200

−100

0

100

200

300

Velo

city

[km

s−1

]

a) Fe XII 192.394 Å (right)

06:2

6:24

.045

(a)

06:2

6:13

.447

(b)

06:2

6:02

.857

(c)

0 20 40 60 80 100 120X (arcsecs)

b) Fe XXIV 192.028 Å (right)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

06:28:16.12006:27:28.12006:26:16.120

06:28:16.12006:27:28.12006:26:16.120

Flow

c)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:04)

0

10

20

30

40

Dis

tanc

e al

ong

arro

w [a

rcse

c]

d)

v1=149 km s−1

v2=76 km s−1

RHESSI 12−25 keV

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

CUT ++

−

−v=14.8 km s−1

v=13.7 km s−1

after reconnectionbefore reconnection

e)

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

06:22 06:24 06:26 06:28 06:30 06:32Start Time (09−Nov−13 06:20:02)

80

100

120

140

dist

ance

alo

ng s

lit [a

rcse

c]

v=14.8 km s−1

v=13.7 km s−1

f)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

AIA 94 Å 06:25:49.120AIA 1600 Å 06:25:52.120

Coronal source

East ribbon

West ribbon

a)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

06:26:14.79006:26:47.63006:27:35.620

06:26:14.79006:26:47.63006:27:35.620

Flows

b)

0 20 40 60 80 100 120X (arcsecs)

−260

−240

−220

−200

−180

Y (a

rcse

cs)

AIA 171 Å 06:25:49.430RHESSI 4.1−4.9 keV 06:25:31+20.0sRHESSI 12.8−15.0 keV 06:25:31+20.0sRHESSI 23.0−27.6 keV 06:23:34+308.8s

c)

0 20 40 60 80 100 120X (arcsecs)

PIL

−400

−200

0

200

400

LOS

mag

netic

fiel

d [G

]

HMI 06:30:27.900AIA 1600 Å 06:25:52.120HMI 06:30:27.900AIA 1600 Å 06:25:52.120

d)

06:22 06:23 06:24 06:25 06:26 06:27 06:28Start Time (09−Nov−13 06:21:51)

10−3

10−2

EM [1

049cm

−3]

Coronal sourceEast sourcefull Sun

06:22 06:23 06:24 06:25 06:26 06:27 06:28Start Time (09−Nov−13 06:21:51)

9

10

11

12

13

T [M

K]

Full Sun!Coronal source!East ribbon!

a)!

b)!

b)!

b)!

a)!

a)!