Alfven waves, Spicules and the partially ionized chromosphere Bart - - PowerPoint PPT Presentation

▶
alfven waves spicules and the partially ionized
SMART_READER_LITE
LIVE PREVIEW

Alfven waves, Spicules and the partially ionized chromosphere Bart - - PowerPoint PPT Presentation

Sep 16, 2023 444 likes •1.01k views

Alfven waves, Spicules and the partially ionized chromosphere Bart De Pontieu Lockheed Martin Solar & Astrophysics Lab Palo Alto, CA, USA Collaborators: Juan Martinez Sykora, Tiago Pereira, Viggo Hansteen, Mats Carlsson, Luc Rouppe van

slide-1
SLIDE 1

Alfven waves, Spicules and the partially ionized chromosphere

Bart De Pontieu Lockheed Martin Solar & Astrophysics Lab Palo Alto, CA, USA

Collaborators: Juan Martinez Sykora, Tiago Pereira, Viggo Hansteen, Mats Carlsson, Luc Rouppe van der Voort, Rob Rutten, Hiroko Watanabe

Papers: Martinez-Sykora, De Pontieu, Hansteen, ApJ, 2012 De Pontieu, et al., ApJL, 2012 Pereira, De Pontieu, Carlsson, submitted to ApJ, 2012 Pereira, De Pontieu, Carlsson, submitted to ApJL, 2012

Thursday, June 21, 2012

slide-2
SLIDE 2

Pedersen resistivity shows horizontal and vertical variations in chromosphere of 6-7 orders of magnitude for ionization equilibrium calculations

ηA = (|B|ρn/ρ)2 ρiνin

Reminder: Pedersen Resistivity ion-neutral collision freq electron density Magnetic field strength neutral density/density ion density/density

Thursday, June 21, 2012

slide-3
SLIDE 3

Pedersen resistivity shows horizontal and vertical variations in chromosphere of 6-7 orders of magnitude for ionization equilibrium calculations

ηA = (|B|ρn/ρ)2 ρiνin

Reminder: Pedersen Resistivity ion-neutral collision freq electron density Magnetic field strength neutral density/density ion density/density

Thursday, June 21, 2012

slide-4
SLIDE 4
  • Strong field case has

Pedersen resistivity that is 3

  • rders of magnitude larger

than weak field case.

  • Strong variation with height
  • f the ambipolar diffusivity

and neutral-ion collision f re q u e n c y. Ve r y l a r g e differences with VAL-C.

  • Important to note that the

ambipolar diffusion and collision frequency changes several orders of magnitude at the same height in the

  • chromosphere. Very large

differences with VAL-C + magnetic field strength.

2D model VAL-C

Weak ambient field Strong ambient field

Diffusivities and collision frequencies highly dependent on equation of state: radiative losses and ionization very important

Thursday, June 21, 2012

slide-5
SLIDE 5
  • Strong field case has

Pedersen resistivity that is 3

  • rders of magnitude larger

than weak field case.

  • Strong variation with height
  • f the ambipolar diffusivity

and neutral-ion collision f re q u e n c y. Ve r y l a r g e differences with VAL-C.

  • Important to note that the

Pedersen resistivity and collision frequency changes several orders of magnitude at the same height in the

  • chromosphere. Very large

differences with VAL-C + magnetic field strength.

2D model VAL-C

Weak ambient field Strong ambient field

Using the VAL/FAL models is not a reliable method of estimating importance in solar atmosphere of various plasma physics effects

Thursday, June 21, 2012

slide-6
SLIDE 6

Time dependent H ionization does not remove discrepancy with VAL/FAL Courtesy Jorrit Leenaarts FAL Best fit to Hion

Ratio between FAL and best fit to Hion

Thursday, June 21, 2012

slide-7
SLIDE 7

Spatial variations still show range of 4-5 orders of magnitude at any one height, even for time dependent hydrogen ionization calculations Generalized Ohm’s Law + H ion Generalized Ohm’s Law

Thursday, June 21, 2012

slide-8
SLIDE 8

Do we know the atomic physics well enough?

  • We calculate the collision

frequency using different methods:

  • Osterbrock (1961) : case A
  • Steiger & Geiss (1989): case B
  • Fontenla et al.(1993): case C
  • The range of values of the

collision frequency, the mean value , and the d e p e n d e n c e w i t h t e m p e r a t u r e d i f f e r considerably between the different methods. The ambipolar diffusion shows a rather significant uncertainty.

  • Note: The axes are in

logarithmic scale.

Collision frequency Ambipolar diffusion Case A Case B Case C

Different formulas for collision frequencies lead to significant uncertainty in Pedersen resistivity

Thursday, June 21, 2012

slide-9
SLIDE 9

Are there really two types of spicules?

Up- and down Parabolic Paths

Lifetime: 3-10 min Velocities: 10-50 km/s Length: ~3,000 km

Active Region Coronal Hole

Mostly upward/fading over whole length

Lifetime: 10-100 s Velocities: 40-150 km/s (Alfvenic?) Length: ~6-10,000 km Type I Type II De Pontieu et al. (2007)

And why do we care?

  • Spicule formation not understood
  • Spicule properties not well constrained?
  • May play significant role in energizing corona/solar wind

Thursday, June 21, 2012

slide-10
SLIDE 10

To provide meaningful statistical sample for active region, quiet Sun, coronal hole automated detection and tracking of spicules required

Thursday, June 21, 2012

slide-11
SLIDE 11

We tracked the temporal and spatial evolution of hundreds of spicules for each type of region Pereira, De Pontieu, Carlsson, 2012

Thursday, June 21, 2012

slide-12
SLIDE 12

Spicules around the limb

Thursday, June 21, 2012

slide-13
SLIDE 13

Spicules around the limb

Coronal Hole Quiet Sun

Thursday, June 21, 2012

slide-14
SLIDE 14

Spicules around the limb

Coronal Hole Active Region

Thursday, June 21, 2012

slide-15
SLIDE 15

Are there two different types of spicules?

Thursday, June 21, 2012

slide-16
SLIDE 16

Are there two different types of spicules?

Thursday, June 21, 2012

slide-17
SLIDE 17

Are there two different types of spicules? Yes.

Thursday, June 21, 2012

slide-18
SLIDE 18

Are there two different types of spicules? Yes.

Fast (30-100 km/s), short-lived (20-150s) type II dominate in QS, CH Slower (10-50 km/s), long-lived (100-500s) type I dominate in AR

Thursday, June 21, 2012

slide-19
SLIDE 19

Are there two different types of spicules? Yes.

Fast (30-100 km/s), short-lived (20-150s) type II dominate in QS, CH Slower (10-50 km/s), long-lived (100-500s) type I dominate in AR

What are classical spicules (20-30 km/s, 5-10 min)?

Thursday, June 21, 2012

slide-20
SLIDE 20

Are there two different types of spicules? Yes.

Fast (30-100 km/s), short-lived (20-150s) type II dominate in QS, CH Slower (10-50 km/s), long-lived (100-500s) type I dominate in AR

What are classical spicules (20-30 km/s, 5-10 min)? Artefact of (poor) spatio-temporal resolution (Pereira, De Pontieu, Carlsson, 2012)

Thursday, June 21, 2012

slide-21
SLIDE 21

Thursday, June 21, 2012

slide-22
SLIDE 22

Thursday, June 21, 2012

slide-23
SLIDE 23

Thursday, June 21, 2012

slide-24
SLIDE 24

Are there really two types of spicules? Addressing Zhang et al. (2012)

Coronal Hole Active Region

Thursday, June 21, 2012

slide-25
SLIDE 25

Are there really two types of spicules? Addressing Zhang et al. (2012)

Coronal Hole Active Region

  • Z12 and we analyzed identical datasets
  • Z12 mislabeled AR dataset as QS
  • Z12 claim they see up- and down behavior

in CH, visual inspection shows only upward motion, as does our automated tracking

  • Z12 claim type II’s do not exist because

“artefact from not tracking transverse motion”, but we do find type II’s by tracking transverse motion

  • Z12’s median lifetime x median maximum

velocity does not equal median maximum height...

  • Z12 result suspect, maybe caused by not

tracking spicules?

Thursday, June 21, 2012

slide-26
SLIDE 26

Are there torsional motions (Alfven waves) on spicules?

Spicules dominated by three motions: LOS projection of field-aligned upflows, swaying motions and torsional motions Inclined spectra in spicules indicate red/blueshift pattern across spicule compatible with strong torsional motion of 20-30 km/s

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-27
SLIDE 27

Are there torsional motions (Alfven waves) on spicules?

Spicules dominated by three motions: LOS projection of field-aligned upflows, swaying motions and torsional motions Inclined spectra in spicules indicate red/blueshift pattern across spicule compatible with strong torsional motion of 20-30 km/s

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-28
SLIDE 28

Are there torsional motions (Alfven waves) on spicules?

Spicules dominated by three motions: LOS projection of field-aligned upflows, swaying motions and torsional motions Inclined spectra in spicules indicate red/blueshift pattern across spicule compatible with strong torsional motion of 20-30 km/s

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-29
SLIDE 29

Are there torsional motions (Alfven waves) on spicules?

Spicules dominated by three motions: LOS projection of field-aligned upflows, swaying motions and torsional motions Inclined spectra in spicules indicate red/blueshift pattern across spicule compatible with strong torsional motion of 20-30 km/s

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-30
SLIDE 30

Torsional motions are time-dependent on ~min timescale

Lambda-time plots in one location show lots of wiggles from time- dependent swaying and torsional motions

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-31
SLIDE 31

Monte Carlo simulations constrain parameters well

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-32
SLIDE 32

Monte Carlo simulations constrain parameters well

Assume N spicules with: Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-33
SLIDE 33

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-34
SLIDE 34

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-35
SLIDE 35

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-36
SLIDE 36

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-37
SLIDE 37

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-38
SLIDE 38

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-39
SLIDE 39

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-40
SLIDE 40

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-41
SLIDE 41

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical
  • azimuth angle from uniform 0-360 deg

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-42
SLIDE 42

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical
  • azimuth angle from uniform 0-360 deg

Lambda Space

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-43
SLIDE 43

Monte Carlo simulations constrain parameters well

Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical
  • azimuth angle from uniform 0-360 deg

Lambda Space 2x swaying: too zig-zagging 2x torsional: too wide in lambda 0x swaying: not enough zig-zagging 0x torsional: not wide enough in lambda

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-44
SLIDE 44

Monte Carlo simulations constrain parameters well

Lambda Time [ s] Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical
  • azimuth angle from uniform 0-360 deg

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-45
SLIDE 45

Monte Carlo simulations constrain parameters well

Lambda Time [ s] 50-100 s swaying periods: too zig-zaggy 50-100 s torsional periods: too zig-zaggy 300-600s swaying periods: not zig-zaggy enough 300-600s torsional periods: not zig-zaggy enough Assume N spicules with:

  • upflows from Gaussian ~70 km/s
  • swaying motions from Gaussian ~15 km/s
  • torsional motions from Gaussian ~30 km/s
  • lifetime from Gaussian around 120s
  • swaying period from uniform 100-300s
  • torsional period from uniform 100-300s
  • wave phase uniform 0-360 deg
  • inclination from uniform at 20 deg from vertical
  • azimuth angle from uniform 0-360 deg

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-46
SLIDE 46

CRISP observations show propagation of torsional waves

Apparent phase speeds of 200-300 km/s ~ Alfven speed

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-47
SLIDE 47

Presence of torsional waves on all spicules can explain morphology of H-alpha wing images on disk

Apparent phase speeds of 200-300 km/s ~ Alfven speed

De Pontieu, Carlsson, Rouppe, Rutten, Hansteen, Watanabe, 2012

Thursday, June 21, 2012

slide-48
SLIDE 48

Conclusions

Thursday, June 21, 2012

slide-49
SLIDE 49

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

Thursday, June 21, 2012

slide-50
SLIDE 50

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

  • 2. Collision frequencies: do we know atomic physics well enough?

Thursday, June 21, 2012

slide-51
SLIDE 51

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

  • 2. Collision frequencies: do we know atomic physics well enough?
  • 3. There really are two types of spicules, with the fast, short-lived

spicules dominating in CH and QS.

Thursday, June 21, 2012

slide-52
SLIDE 52

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

  • 2. Collision frequencies: do we know atomic physics well enough?
  • 3. There really are two types of spicules, with the fast, short-lived

spicules dominating in CH and QS.

  • 4. Classical spicules are an artefact of poor spatio-temporal resolution.

Thursday, June 21, 2012

slide-53
SLIDE 53

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

  • 2. Collision frequencies: do we know atomic physics well enough?
  • 3. There really are two types of spicules, with the fast, short-lived

spicules dominating in CH and QS.

  • 4. Classical spicules are an artefact of poor spatio-temporal resolution.
  • 5. All type II spicules carry strong torsional Alfven waves (20-30 km/s!)

(implications for chromo/coronal heating?, van Ballegooijen et al., 2012!)

Thursday, June 21, 2012

slide-54
SLIDE 54

Conclusions

  • 1. Effects of partial ionization cannot reliably be estimated by using

VAL/ FAL, can be order(s) of magnitude off (dynamic atmosphere, spatial structuring).

  • 2. Collision frequencies: do we know atomic physics well enough?
  • 3. There really are two types of spicules, with the fast, short-lived

spicules dominating in CH and QS.

  • 4. Classical spicules are an artefact of poor spatio-temporal resolution.
  • 5. All type II spicules carry strong torsional Alfven waves (20-30 km/s!)

(implications for chromo/coronal heating?, van Ballegooijen et al., 2012!)

  • 6. Spicules play major role in transport of helicity in solar atmosphere.

Thursday, June 21, 2012

slide-55
SLIDE 55

LOS mass flow [km/s] LOS torsional motion =0 =40 km/s

  • 10
  • 20
  • 30
  • 40

+10 +20 +30 +40 Appearance of flux tube with field-aligned flow and strong transverse motion critically dependent on viewing angle (and mix of motions) Observer is looking from above the plane of the screen at an angle that is not 90 degrees Note that if there are no mass flows, but transverse swaying motions of the whole flux tube with the same amplitude, the effects would be the same

Why don’t we see rows of blue/red flux tubes everywhere?

Thursday, June 21, 2012