Observations and Modeling of Chromospheric Spicules

1
Observations and Modeling of Chromospheric
Spicules

• Bart De Pontieu
• Lockheed Martin Solar Astrophysics Lab

Thanks to Robertus Erdélyi Stewart James
(Sheffield University) Ineke De Moortel (St.
Andrews) Alfred de Wijn (Utrecht) Tom Metcalf
(LMSAL) with thanks to Tom Berger (LMSAL) for the
SOUP filter
2
Outline

• Introduction Spicules, Mottles, Fibrils?
• Observations
• Dark Mottles Spicules?
• Magnetic Fields
• EUV/UV counterparts
• Periodicities/Oscillations
• Modeling
• p-mode driver 1D simulations
• 2D MHD simulations

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
3
Introduction Spicules,Mottles, Fibrils?
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Spicules jets usually observed at the limb
(superposition!) in chromospheric lines in
emission speeds 10-30 km/s, heights of 5-10
Mm, lifetimes of 3-15 min, widths of order 0.1-1
Mm (close to current resolution!)
4
Introduction Spicules,Mottles, Fibrils?
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Dark Mottles disk equivalent of limb spicules?
5
Introduction Spicules,Mottles, Fibrils?
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Active Regions Horizontal Fibrils, vs. short,
more vertical Fibrils. Spicule like jets are
present in ARs, especially above plage, but
shorter (2-4 Mm) and shorter lived (3-6 min).
6
Introduction Spicules,Mottles, Fibrils?
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Active Regions Horizontal Fibrils, vs. short,
more vertical Fibrils. Spicule like jets are
present in ARs, especially above plage, but
shorter (2-4 Mm) and shorter lived (3-6 min).
7
Introduction So why do we care?

1. Dominate and drive much of the dynamics of the
   magnetized chromosphere quiet sun network and
   active region plage
2. Major part of chromospheric physics NOT
   understood problem for all of solar physics
   since all magneto-convective energy driving
   coronal heating and solar wind passes through
   region!
3. Carry mass flux of 100 times of solar wind flux
   up to coronal heights (do they contribute?)

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
8
Introduction Major Outstanding Issues

1. Are spicules/mottles/fibrils all part of same
   phenomenon?
2. Are they driven by waves/shocks or flows in the
   photosphere? What causes periodicities?
3. What role does reconnection play? Are there
   opposite polarities at footpoints? Are they
   related to explosive events?
4. What role do they play in the coronal mass/energy
   balance? How do they relate to UV spicules?

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
9
Observations Spicules/Mottles/Fibrils
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Confusion on mottles/spicules (Grossman-Doerth
Schmidt, 1992) TRACE real mass motion in dark
mottles (e.g., moss)
10
Observations Magnetic Fields
Hanle effect He I D3, Sac Peak (0.7-70 G) At
3,500 km mostly 10 G (Q/U, V is noise!) Some
probably up to 40 G? 40 from vertical, aligned
with spicules?
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Lopez Ariste Casini, 2005
11
Observations Magnetic Fields
He I 10830 Ca II 8542 Ca II 8498
I Q U V
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
He I 10830 Ca II triplet, Sac Peak No Hanle
modelling dependence field is present! Tlt13,000
K and non-thermal line-broadening Probing
different parts of spicule?
Solar-B SP observations, scan of 3 at the limb
Socas-Navarro Elmore, 2005
12
Observations UV/EUV counterparts

1. Which (if any) among the many energetic UV
   jet-like features such as explosive events,
   blinkers, UV spicules are associated with H?
   spicules?
2. Are these UV spicules signs of evaporation
   (e.g., Budnik et al., 1998) or of hot, thin
   sheaths around cold spicules (Withbroe, 1983)?
   Limits on models!
3. Current UV instrumentation a bit marginal to
   address this issue given lt 1 diameter of
   spicules.

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
13
Observations UV/EUV counterparts
Xia et al. (2005) properties of UV spicules very
similar to H? spicules lifetime 3-15 min, 10-20
heights, some with periodicities around 5 min,
spicules occur for T lt 0.4 MK
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
14
Observations UV/EUV counterparts
Teriaca et al. (2004) Reconnection driven
spicules and explosive events connected?
Two-step mechanism (Chae et al., 1998) initial
reconnection (magnetic islands as H? upflow
events), followed by fast reconnection with
overlying fields bi-directional jets
(EE) Madjarska Doyle (2003) Blinkers related
to spicules, but not to explosive events?

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
15
Observations UV/EUV counterparts

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
TRACE C IV emission highly variable (lots of
blinkers), associated with strongly inclined
chromospheric active region fibrils
16
Observations UV/EUV counterparts

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Not all fibrils associated with explosive events,
or with UV emission, especially the shorter, less
inclined fibrils (the active region equivalent of
spicules or mottles).
17
Observations UV/EUV counterparts

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Correlation between H?700 mÅ (red wing) and
TRACE C IV 1550 Å, typically more at periphery of
moss regions (De Pontieu et al., 2003) Heating of
downflowing spicules? De Wijn De Pontieu, 2005
18
Observations UV/EUV counterparts
Solar-B SOT/FPP 10 NFI images of 800x800 0.08"
pixels at 30 s cadence Fe I 630.2 nm
dopplergram/longitudinal magnetogram (4 images)
Mg Ib 517.2 nm
dopplergram/longitudinal magnetogram (4 images)
Ha 656.3 nm -700/-350 mA filtergrams
(2 images) SP full Stokes map of
1.9"x64" FOV in normal map mode
(12 steps of 0.16" and 400 0.16" pixels
along slit) EIS Start with one "wide
slit" (40" wide) exposure in He II 256, Si VII
275, Fe XII 193, Fe XIII 202, Fe XIV 274, Fe XV
284 for co-alignment purposes.
13 spectral windows containing He II 256 A, Mg V
276, Mg VI/Fe XIV 270, Mg VII/Si VII 278, Si
VII 275, Fe XII 186, Fe XII 195, Fe XIII 202, Fe
XIII 203, Fe XIV 264, Fe XIV 274, Fe XV 284, S
XI 285 at 30 s cadence (5.2 s exp), read out
64" along slit, co-aligned with SOT/FPP
pointing, scan 5" in E-W XRT logT6.1
partial Frame Images (PFI) FOV 256"x256"
1"/pix 4 channels Al/poly, C/poly,
Be/thin, Be/med 30 sec cadence, to provide
context and study EUV absorbing spicules and/or
heating events above plage/network

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
19
Observations Periodicities/Oscillations

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Many short fibrils above AR plage are
quasi-periodic with periods around 5 minutes
(3-10 min) (De Pontieu, Erdelyi, de Wijn, 2003)
Some QS mottles are also quasi-periodic with 5
min (Tziotziou et al, 2003, 2004), QS spicules
(Pasachoff et al., 2005) and even UV spicules
(Xia et al., 2004)
Solar B SOT/FPP Ha scans at 20 s cadence for
seeing-free statistical study of periodicities,
simultaneous with BFI G-band images and NFI 5576
Å Dopplergrams
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Observations Periodicities/Oscillations
Quasi-periodic spicules ? oscillations in upper
TR moss

1. Variable P 200-600 s, ltPgt 34960 s
2. Limited to patches of 1 to 2 arcseconds
3. Oscillations often at periphery of a moss/plage
   patch
4. Oscillations sometimes coherent over 5
   arcseconds (see de Wijn De Pontieu, 2005)

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
De Pontieu, Erdelyi, de Wijn, 2003
21
Modeling MDI driven 1D HD
Photospheric Source for Periodic Spicules?

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight

• Five minute power in photosphere is not enhanced.
  
• p-modes are evanescent

De Pontieu, Erdélyi, James, 2004
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Modeling MDI driven 1D HD
Modeling vs. Observations!
Observed spicule occurrence negative of TRACE
171Å intensity. Varying spicule filling factors
lead to mismatch in amplitude
Predicted and observed spicule occurrence agree
reasonably well.

1. Active region spicules (fibrils) QS spicules
   reconnection?
2. Periodic spicules from p-mode leakage on inclined
   or twisted flux tubes
3. Most spicules not periodic formed by non-linear
   evolution of photospheric velocities granulation
   (e.g., rebound-shock model, Hollweg, Sterling, et
   al., 1982,1988) and propagating wave signal
4. 2/3D simulations with proper non-LTE radiation
   treatment necessary

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
De Pontieu, Erdélyi, James, 2004
23
Modeling MDI driven 1D HD
Natural result of spicules coronal waves/shocks
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Slow mode magneto-acoustic waves Variable
Amplitude 4.11.5 Variable P 32174 s for
plage Limited to 2-4 arcseconds Loops
significantly inclined (45) (De Moortel et
al., 2002)
De Pontieu, Erdélyi, De Moortel, 2005
24
Observations Wave/Shock Driver
Solar-B SOT/FPP 12 NFI images of 800x800 0.08"
pixels at 30 s cadence 1 BFI image of
1208x1208 0.053" pixels at 30 s cadence
NFI Fe I 6302.5 nm dopplergram/longitudinal
magnetogram (4 im) Mg Ib 517.2 nm
dopplergram/longitudinal magnetogram (4 im)
Ha 656.3 nm -700/-350/350/700 mÅ
filtergrams (4 images) BFI G-band
430.5 filtergram (1 image) Telemetry
304 kbit/s EIS Start with one
"wide slit" (40" wide) exposure in He II 256, Si
VII 275, Fe XII 193, Fe XIII 202, Fe XIV
274, Fe XV 284 for co-alignment purposes
13 spectral windows containing
He II 256 A, Mg V 276, Mg VI/Fe XIV 270, Mg
VII/Si VII 278, Si VII 275, Fe XII 186, Fe XII
195, Fe XIII 202, Fe XIII 203, Fe XIV 264, Fe
XIV 274, Fe XV 284, S XI 285 at 30 s cadence
(14.2 s exp), read out 64" along slit, co-aligned
with SOT/FPP pointing, scan 2" in E-W
Telemetry 26.6 kbit/s XRT logT6.1
images at full resolution, partial frame of
256"x256" to provide context and study EUV
absorbing spicules above plage/network. Partial
Frame Images (PFI) FOV 256"x256" 1"/pix
4 channels Al/poly, C/poly, Be/thin,
Be/med 30 sec cadence

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
25
Modeling 2D MHD
Log Temperature Upward Velocity
(Bright corona)
(Bright up, 10 km/s)
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
White lines field lines, green plasma ?1,
orange ?0.1 or 10
2D MHD simulations driven by sinusoidal driver
(400 s) in low ?, tilted flux tube
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Modeling 2D MHD
Log Temperature Upward Velocity
(Bright corona)
(Bright up, 10 km/s)
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
White lines field lines, green plasma ?1,
orange ?0.1 or 10
2D MHD simulations driven by MDI driver in low ?,
tilted flux tube (reconnection AND wave driven
jets)
27
Modeling the real solar atmosphere
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Photospheric flux tubes highly dynamic,
continuously jostled by convection.
28
Modeling 2D radiative MHD
Courtesy Viggo Hansteen
Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight
Role of variations in chromospheric/coronal
heating in spicules (Athay, 2000)? Do thermal
instability resulting low pressures lead to
spicules (Hammer Nesis, 2003, 2004)? Ensure
relevant microphysics included, e.g., partial
ionization, James Erdelyi, 2002-2004)
29
Conclusions

1. Significant mass motions involved in
   mottles/fibrils, most probably related to
   spicules at limb
2. Spicules aligned with magnetic field of 10-40 G,
   often inclined by 30
3. Confusion on UV counterparts some spicules
   related to explosive events/blinkers, but others
   not?
4. Reconnection vs. non-linear wave/shock driving?
   Are multiple mechanisms at work?
5. Why are AR spicules lower and why do they have
   shorter lifes? Height of TR? Reduced wave power?
   Lack of opposite polarity?
6. What causes quasi-periodic, coherent behaviour of
   spicules?
7. Spicule models should not (cannot?) be isolated
   from coronal/chromospheric heating! Hot
   magnetized chromosphere?
8. Need high resolution (lt0.5) imaging and
   spectroscopy in visual (multiple lines!), IR and
   UV Solar-B
9. Need 2D/3D radiative MHD simulations, but
   important to consider which microphysics to
   include, e.g., partial ionization

Bart De Pontieu demonstration put something on
a table (say a ball) Why does it stay there? Is
it being acted on by a force? Yes weight!!!
Explain weight