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) 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: 5min Assumption L=130,000km n e =10 9 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 line, 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 intensity peak in s Continuum peak in s Doppler velocity peaks at 300s and 700s Minarovjech, M. et al. 2003, SoPh, 213, 269.

SOHO Spectrometers SUMER (Solar Ultraviolet Measurements of Emitted Radiation) UV Spectrometer ( Å) CDS (Coronal Diagnostic Spectrometer) NIS( Å, Å), GIS( Å) UVCS (Ultraviolet Coronagraph Spectrometer) Lyα(1216Å), O IV(1037Å), WL(Linear Polarization) Observation range R  Observe temporal and spatial variations of: Line width, Doppler velocity, and Intensity.

Polar Plumes SOHO/CDS No scanning mode O V 629Å (logT e =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. FluctuationAlfvenAcoustic DensityNoYes VelocityYes

Density Fluctuation SOHO/UVCS WLC (polarimeter) pB value: related to electron density Strong power near mHz (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 10 6 K corona

Equatorial Corona SOHO/CDS Off limb observation of quiet corona O V and Mg X Line width variation up to the height of 140,000km Harrison, R.A. et al. 2002, A&A, 392, 319. Non-thermalInstrumental

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 T e =8x10 5 K), UVCS, and LASCO Electron density distribution up to 8R  N e ∝ r -2 above 4R  Doyle, J.G. et al. 1999, A&A, 349, 956.

Line Broadening Sharp increase above 1.5R  Line width : thermal (2kT i /M) 1/2 + non-thermal T i ~ 1.6 x 10 6 K Doyle, J.G. et al. 1999, A&A, 349, 956.

Non-thermal Velocity Theoretical relation of undamped propagating Alfven wave(Hollweg 1990) Doyle, J.G. et al. 1999, A&A, 349, 956. 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, visit September 2004 University of St Andrews, UK

Template Item Reference