Review: Recent Observations on Wave
HeatingS. Kamio
Kwasan and Hida ObservatoriesKyoto University
Observing wave• Intensity
Density 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
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• Observed period: 5
min• Assumption
L=130,000kmne=109 cm-3
B=20G
fast kink mode
Aschwanden, M. J. et al. 1999, ApJ, 520, 880.
Visible Light• Coronagraph at Lomnicky
Stit and Norikura• Fe XIV 5303Å (Green lin
e, T=2MK) and continuum
• Temporal variation for 2 hours
Minarovjech, M. et al. 2003, SoPh, 213, 269.
White light pB map, contrast enhanced
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• 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• SOHO/CDS
No scanning modeO V 629Å (logTe=5.4) Intensity and velocity variations in 1 hour
Banerjee, D. et al. 2000, SoPh, 196, 63.
•Plumes are denser and cooler plasma, where high speed solar wind is generated.
•CDS Slit covers polar coronal hole and plume
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.
Fluctuation
Alfven Acoustic
Density No Yes
Velocity Yes Yes
Density Fluctuation• SOHO/UVCS
WLC (polarimeter)pB value: related to electron density
• Strong power near1.6-1.8mHz (10min)
Ofman, L. et al. 2000, ApJ, 529, 592.
•Density fluctuation appear intermittently with coherence time of 30 min
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
Ofman, L. et al. 2000, ApJ, 529, 592.
Comparable to the sound speed in 106K corona
Equatorial Corona• SOHO/CDS
Off limb observation of quiet coronaO V and Mg X
• Line width variationup to the height of 140,000km
Harrison, R.A. et al. 2002, A&A, 392, 319.
)(
iMkT
Non-thermal Instrumental
Line Narrowing• Line width decreased
by 10% above 50,000km
• Amplitude of wave must increase in decreasing dentisy.
Line narrowing suggests wave dissipation
Harrison, R.A. et al. 2002, A&A, 392, 319.
limb
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• 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• Theoretical relation o
f undamped propagating Alfven wave(Hollweg 1990)
Doyle, J.G. et al. 1999, A&A, 349, 956.
4/12/12 v
Good agreement with the observation below 1.2R
Summary• Previous papers
Coronal 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
• For more information, visithttp://www.soho15.org/
6-9 September 2004University of St Andrews, UK
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