Review recent observations on wave heating
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Review: Recent Observations on Wave Heating. S. Kamio Kwasan and Hida Observatories Kyoto University. Observing wave. Intensity Density fluctuation Apparent motion of coronal structure Doppler velocity Bulk motion of plasma Line width variation Unresolved motion (non-thermal).

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Review: Recent Observations on Wave Heating

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Review recent observations on wave heating

Review: Recent Observations on Wave Heating

S. Kamio

Kwasan and Hida Observatories

Kyoto University


Observing wave

Observing wave

  • IntensityDensity fluctuationApparent motion of coronal structure

  • Doppler velocityBulk motion of plasma

  • Line width variationUnresolved motion (non-thermal)

Because corona is optically thin, observation is effected by line of sight integration.


Loop oscillation

Loop Oscillation

  • Loop oscillation observed in M4.6 flare (TRACE 171Å)

  • Oscillation period at the loop top: 276±25s

Aschwanden, M. J. et al. 1999, ApJ, 520, 880.


Wave mode

Wave mode

  • Observed period: 5min

  • AssumptionL=130,000kmne=109 cm-3B=20Gfast kink mode

Aschwanden, M. J. et al. 1999, ApJ, 520, 880.


Visible light

Visible Light

  • Coronagraph at Lomnicky Stit and Norikura

  • Fe XIV 5303Å (Green line, T=2MK) and continuum

  • Temporal variation for 2 hours

White light pB map, contrast enhanced

Minarovjech, M. et al. 2003, SoPh, 213, 269.


Wavelet analysis

Wavelet Analysis

  • Line intensitypeak in 220-320s

  • Continuumpeak in 500-950s

  • Doppler velocitypeaks at 300s and 700s

Minarovjech, M. et al. 2003, SoPh, 213, 269.


Soho spectrometers

SOHO Spectrometers

  • SUMER(Solar Ultraviolet Measurements of Emitted Radiation) UV Spectrometer (660-1610Å)

  • CDS(Coronal Diagnostic Spectrometer)NIS(308-381Å, 513-633Å), GIS(151-785Å)

  • UVCS(Ultraviolet Coronagraph Spectrometer)Lyα(1216Å), O IV(1037Å), WL(Linear Polarization)Observation range 1 - 12R

Observe temporal and spatial variations of:Line width, Doppler velocity, and Intensity.


Polar plumes

Polar Plumes

  • SOHO/CDSNo scanning modeO V 629Å (logTe=5.4) Intensity and velocity variations in 1 hour

  • Plumes are denser and cooler plasma, where high speed solar wind is generated.

  • CDS Slit covers polar coronal hole and plume

Banerjee, D. et al. 2000, SoPh, 196, 63.


Wavelet analysis1

Wavelet Analysis

  • Strong Power 1.65mHz(P=10min)

  • Intermittent nature Coherence time of 30min

  • Intensity oscillation is caused by slow magneto-acoustic wave

Banerjee, D. et al. 2000, SoPh, 196, 63.


Density fluctuation

Density Fluctuation

  • SOHO/UVCSWLC (polarimeter)pB value: related to electron density

  • Strong power near1.6-1.8mHz (10min)

  • Density fluctuation appear intermittently with coherence time of 30 min

Ofman, L. et al. 2000, ApJ, 529, 592.


Group speed

Group Speed

  • Time lag between 1.9 and 2.1R656±165s

  • Assuming solar speed is 90±20 km/s, wave speed is 120±58km/s

Comparable to the sound speed in 106K corona

Ofman, L. et al. 2000, ApJ, 529, 592.


Equatorial corona

Equatorial Corona

  • SOHO/CDSOff limb observation of quiet coronaO V and Mg X

  • Line width variationup to the height of 140,000km

Non-thermal

Instrumental

Harrison, R.A. et al. 2002, A&A, 392, 319.


Line narrowing

Line Narrowing

  • Line width decreased by 10% above 50,000km

  • Amplitude of wave must increase in decreasing dentisy.

     Line narrowing suggests wave dissipation

limb

Harrison, R.A. et al. 2002, A&A, 392, 319.


Polar coronal hole

Polar Coronal Hole

  • SOHO/SUMER(Si VIII Te=8x105K), UVCS, and LASCO

  • Electron density distribution up to8R

  • Ne∝r-2 above 4R

Doyle, J.G. et al. 1999, A&A, 349, 956.


Line broadening

Line Broadening

  • Sharp increase above 1.5R

  • Line width :thermal (2kTi/M)1/2 + non-thermal

  • Ti ~ 1.6 x 106K

Doyle, J.G. et al. 1999, A&A, 349, 956.


Non thermal velocity

Non-thermal Velocity

  • Theoretical relation of undamped propagating Alfven wave(Hollweg 1990)

Good agreement with the observation below 1.2R

Doyle, J.G. et al. 1999, A&A, 349, 956.


Summary

Summary

  • Previous papersCoronal wave and signature of dissipation have been found.

  • Improved spectral resolution of Solar-B/EIS will enable us to study the corona in detail.

  • Connection between chromosphere and corona:Spectroscopy of chromospheric lines with ground based stations and Solar-B/SOT


Call for papers

Call for Papers

  • For more information, visithttp://www.soho15.org/

6-9 September 2004University of St Andrews, UK


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