Properties of Prominence Motions Observed in the UV

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Properties of Prominence Motions Observed in the
UV

• T. A. Kucera (NASA/GSFC)
• E. Landi (Artep Inc, NRL)

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Intent of this investigation
To make observations with which to test models of
prominences formation and the nature and cause
of flows in prominences by measuring the thermal
and kinetic properties of moving prominence
features.
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Previous observations Prominences movies
show prominences made up of moving features with
velocities typically 5-20 km/s in H? (sometimes
faster) and often 30 km/s and higher in UV and
EUV. Some of these motions apparently
multi-thermal over a wide range of temperatures
(104-105K), and lasting for 10s of
minutes. Question what causes motions in
prominences? How can we test models of these
processes?
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Simplistic Description of Model Predictions
Model Kinetic Thermal
Jets Can be quite fast (80 km/s no problem) If from chromosphere should show cooling
Chromospheric evaporation Current models, slow motions (10 km/s) Multi temperature blobs for extended periods, thermal structure in simple 1-D model
Wave acceleration slow motions (10 km/s) ??
Upward magnetic field steady models slow (10 km/s) Cool? heating via reconnection?
Thermal wave no Doppler shift
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Observational problem In order to study the
thermal characteristics of these motions you need
to study the motions with a high temporal
cadence (1 image/min), good spatial resolution
(gt2") in a range of optically thin, resolved
spectral lines. This combination cant be done
in 2D with any existing instrument. Technique
Use a UV spectrograph (SOHO/ SUMER or CDS) in
sit and stare mode with a narrow slit (i.e.,
1-D). Combine with imaging instrument to get 2-D
information.
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Observations
April 17, 2003 SUMER, CDS, TRACE
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Data Characteristics
Inst. cadence spatial res. spectral res. (FWHM) wave band
SUMER 90s 2" 86 mA 750-790 Å
CDS 52s 4-8" 2.6 A lines in 513-633 Å
TRACE 60-91 s 1" ------- 1600 Å 1216 Å 195 Å
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SUMER spectrum
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SUMER Lines
Ion Wavelength Log T (K)
N III 764.34 Å 4.9
N III 763.33 Å 4.9
N IV 765.15 Å 5.2
S V 786.47 Å 5.2
O V 760.43,760.21 Å 5.4
O V 761.99 Å 5.4
Ne VIII 770.42 Å 5.8
Mg VIII 782.34 Å 5.9
Mg VIII 762.65 Å 5.9
S XI 783.01 Å 6.2
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Observations
Prominence in days before observations
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TRACE 1216 Å bandpass (Lyman ?)
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TRACE 1600 Å bandpass C IV, Si Continuum, Fe II
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TRACE 195 Å bandpass Fe XII
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TRACE 1600 Å (C IV, Si Continuum, Fe II)
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SUMER N IV 765.15 Å
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• Three checks for temperature variations
• Line ratios
• Differential Emission Measure (DEM)
• Feature shifts

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Differential Emission Measure
Assumes Ionization Equilibrium Optically thin
plasma Smooth function (spline) No material
below 104 K or above 107 K
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• Summary of Observations
• Consistent with last study
• Many features going 25 km/s
• Visible along slit for 15 min, last longer
  in TRACE movie.
• Doppler shifted (in UV!) - real motions
• 8?104 to 2.5 ?105 for one set of repeating
  features
• 8?104 to1.5 ?106 K for one abrupt feature
• To within the ability to measure with the SUMER
  data there is no evidence of cooling with time in
  features D-E.

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To Do

• Complete kinetic information for sources
• Continue to work on DEM for thermal energy
  content.
• Determine if there are any models which can
  predict this information.
• Coronal Evaporation Model of Antiochos et al
  1999, and Karpen et al 2001
• Reconnection Jet Models (Wang 1999, Litvinenko
  Martin 1999)