Filament threads and oscillations

1
Filament threads and oscillations

• Yong Lin1, Oddbjørn Engvold1,
• Luc Rouppe van der Voort1,2, Michiel van Noort1,3

1 Institute of Theoretical Astrophysics,
University of Oslo, Norway 2 Center of
Mathematics for Applications, University of Oslo,
Norway 3 The Institute for Solar Physics of the
Royal Swedish Academy of Sciences, AlbaNova
University Center, Sweden
2

• Observations of oscillations in filaments
• Classifications
• Oscillations in a quiescent filament
• Characteristics of filaments in high resolution
• Propagating waves in filament threads
• Spatially coherent waves
• Concluding remarks

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Observations

• Indicators Vlos, Line intensity, line width
• Classifications
• - Large amplitude
• gt 20 km/s
• (winking filament)
• - Small amplitude
• lt 3 km/s

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Small Amplitude Oscillations
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Small Amplitude Oscillations

• Are continuously present
• Have periods of
• - Very short (lt 1 min)
• - Short (1 - 20 min)
• - Intermediate (20 - 40 min)
• - Long (40 - 1 hr)
• - Ultralong (gt 2 hrs, Foullon et al. 2004)

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SST 2004 filament target
Ha, Aug. 22, 2004, SST (N 24.5 W 1.2)
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Filament thin threads

• Width 0.20.3 Length 520 Plasma
  filling

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Small-amplitude Oscillations
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Wave propagation along threads
Vph1 8.8 km/s P1 5.2 min Vph2 10.2
km/s P2 5.6 min
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Flows and oscillations

Vph15 km/s ?4.5 arc sec
P3.6 min
Reference system tied to wave motion
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Comparison with the Fibril models

• W/L 0.1
• ?e??c 0.6, ?p??c 200
• B0 5 G
• VAc 488 km/s
• L 5 x 104 km

(Díaz et al. 2001)
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Spatial coherence of oscillations
Area1 3.4 x 10 arc sec Duration 18 min Cadence
27 sec

• Period 3.6 min

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Spatial coherence of oscillations
Duration 138 min Cadence 64 sec Slice size
58x1.4

• Period 26 min.

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Multifibril in a Cartesian system

• Periods in the range of
• 5-20 min
• The fibrils end up with oscillating in phase.
• Filling factor can be used to estimate periods.

• Díaz et al. 2002, 2003, 2005
• Díaz and Roberts, 2006

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Concluding remarks

• Short period (39 min) waves propagating along a
  number of thin threads.
• Some threads seem to cross-talk and oscillate
  together (most pronounced for longer periods).
• The detected short period oscillations appear to
  favor the fast MHD modes of the fibril models.
• Some waves are found to be accompanied with mass
  flows.