high cadence iris observations of evaporating flare ribbon ... · • remarkable curves for 81...
TRANSCRIPT
High cadence IRIS observations of evaporating flare ribbon sources
David Graham, Gianna Cauzzi, Luca Zangrilli INAF - Osservatorio Astrofisico di Arcetri
September 10th 2014
• X1.6 17:45 UT
• Sit and stare - 9.4 second cadence
• Coronal + chromospheric temperature lines
• Fe XXI + Mg II
• 0.33’’ x 0.167’’ pixel size
1400Å Slitjaw Image (Si IV)Ribbon dynamics and characteristics
• Every slit pixel shows a unique and complete flare evolution (81 flares for the price of 1!)
-180 -160 -140 -120 -100 X (arcsecs)
80
100
120
140
160
180
Y (a
rcse
cs)
17:26:01
17:30:05
110
120
130
140
150
Y (a
rcse
c)
17:30:42
-160 -150 -140 -130 -120
17:33:50
X (arcsec)-160 -150 -140 -130 -120 -110
100
110
120
130
140
150
Y (a
rcse
c)
X (arcsec)
17:37:55
1400Å Slitjaw
SPEX FERMI GBM Count Flux vs Time
17:30 17:45 18:00 18:15Start Time (10-Sep-14 17:15:00)
10-4
10-2
100
102
104
coun
ts s
-1 c
m-2 k
eV-1
Detectors: NAI_024.6 to 15.2 keV (Data with Bk)15.2 to 24.3 keV (Data with Bk)24.3 to 50.9 keV (Data with Bk)50.9 to 98.8 keV (Data with Bk)98.8 to 296.4 keV (Data with Bk)296.4 to 601.2 keV (Data with Bk)601.2 to 2000.0 keV (Data with Bk)
14-May-2015 13:17
Fe XXIC II
Constrained Si II (from Fe XII window)
Fe XXI Window - Fitting example
Fe II tied centroids
1352.5 1353.0 1353.5 1354.0 1354.5Wavelength (Å)
0
200
400
600
800
Inte
nsity
(pho
tons
)
Si II Fe II Fe II C IH2 Si II
Mg II (2791.55 Subordinate line) – Bisector analysis (Ding et al. 1995)
Use the 30% bisector for analysis - maximum shift without including background or unknown blends
Fe XXI fitted (green) - 1354.1 rest wavelength
1352.5 1353.0 1353.5 1354.0 1354.5Wavelength (Å)
0
200
400
600
800
Inte
nsity
(pho
tons
)
17:29:58
1352.5 1353.0 1353.5 1354.0 1354.5Wavelength (Å)
0
100
200
300
400
500
600In
tens
ity (p
hoto
ns)
17:30:45
1352.5 1353.0 1353.5 1354.0 1354.5Wavelength (Å)
0
100
200
300
400
Inte
nsity
(pho
tons
)
17:33:52
1352.5 1353.0 1353.5 1354.0 1354.5Wavelength (Å)
0
100
200
300
400
Inte
nsity
(pho
tons
)
17:37:47
2791.2 2791.4 2791.6 2791.8 2792.0Wavelength (A)
0
2
4
6
8
10
Inte
nsity
x10
4 (pho
tons
)
2791.2 2791.4 2791.6 2791.8 2792.0Wavelength (A)
0
2
4
6
8
Inte
nsity
x10
4 (pho
tons
)
2791.2 2791.4 2791.6 2791.8 2792.0Wavelength (A)
0
1
2
3
4
5In
tens
ity x
104 (p
hoto
ns)
2791.2 2791.4 2791.6 2791.8 2792.0Wavelength (A)
0
1
2
3
4
Inte
nsity
x10
4 (pho
tons
)
• Section of 81 pixels
• Ribbon moves along slit at a constant rate
• Co-spatial Mg II intensity and condensation flows
• Mg II and Fe XXI flows co-spatial (?)
• Apparent delay in Fe XXI flows (~65s)
Mg II 15 & 30 km/s
Fe XXI >270 (yellow), >200 (dark blue), >100 (blue) km/s
17:26 17:28 17:30 17:32 17:34Start Time (10-Sep-14 17:25:11)
114
116
118
120
122
124
126
128
17:26 17:28 17:30 17:32 17:34Start Time (10-Sep-14 17:25:11)
114
116
118
120
122
124
126
128
Y (a
rcse
c)
10
• Superposed epoch analysis of all pixels (colour maximum 20 instances)
• Remarkable curves for 81 flaring pixels
• Evaporation duration ~ 500 seconds / Condensation ~ 60 seconds. (Fisher 1986 model)
• Previous observed condensation time ~ 2-3 minutes (Ichimoto & Kurokawa 1984, Ding 1995 et al.)
0 240 480 720 960Time (s)
-400
-300
-200
-100
0
100km
s-1
0 240 480 720 960Time (s)
-400
-300
-200
-100
0
100km
s-1
Fe XXI Velocity
0 30 60 90 120 150 180Time (s)
0
10
20
30
40
km s
-1
0 30 60 90 120 150 180Time (s)
0
10
20
30
40
km s
-1
Mg II Velocity (30% bisector)
11
• Velocity profile - good proxy for energy deposition in the chromosphere (Fisher 1986/89)
• Average temporal profile + average spatial profile
• Upper limit to the size - 1.5” (includes ribbon inclination and movement)
• Ribbon’s apparent motion ~0.025”/s
0 10 20 30 40 50 60Data Step
0
10
20
30
Velo
city
km
s-1
FWHM Time = 28.2 sFWHM Spatial = 1.53"
Mg II (sub) Mean Velocity ProfileRibbon Characteristics
Conclusions
12
• IRIS gives us the most complete view of evaporation/condensation to date
• Evaporation and condensation flows - potentially co-spatial (possible delay)
• Fe XXI line is always completely blue-shifted
• Sources show remarkably similar evolution - flare is a progression of single events
• Condensation time of ~ 60 seconds close to simulation.
• Ribbon size <1.5’’ Excitation time ~ 30 seconds
• Ribbon spatial and temporal scales are essential inputs for modelling (i.e determining the input flux for RADYN)
“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)”