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

Template• Item

Reference