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Imaging The Active Region TR Imaging The Active Region TR With The CDS Wide SlitWith The CDS Wide Slit

Mike Marsh

Centre for Astrophysics, University of Central Lancashire, Preston, UK

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The Wide Slit

Mg IX368 Å

He I584 Å

O V629 Å

•90˝× 240˝ FOV•26s cadence•Produces intensity images (not rastered) in He I, O V & Mg IX•But no spectral data

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Wide Slit Calibration

Mg IX uncalibrated Mg IX calibrated

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AR 10570

TRACE 171 Å

TRACE 1600 Å

TRACE WLEIT 171 Å

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AR 10570

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TRACE 1600 Å

TRACE 1600 +171 Å

TRACE 1600 +O V

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Composite MovieTRACE 1600 Å O V TRACE 171 Å

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Composite MovieO V TRACE 171 Å

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Rastered data

Rastered data gains line profile data, but loses time variability information

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MDI WL + O V + 171TRACE 171 + O

VTRACE 171

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Fourier power maps

Power significant to 95%

3 min band (4.7 – 6.6 mHz) (150 – 210 s)

3-min umbral oscillationsBeckers & Tallant (1969), Gurman (1982), Fludra (2001), Brynildsen (2002)

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3 min He I time series

• He I oscillation amplitude ~2%

• FFT has 2 dominant periods ~(6.1 & 7.1) mHz(140 & 160) Seconds

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3 min O V time series

• O V oscillation amplitude ~4%

• FFT has 2 dominant periods ~(5.9 & 7.3) mHz(140 & 170) Seconds

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AR 10570 with TRACE

~80 kms-1 projected velocity cf. De Moortel et al. (2002) Robbrecht et al. (2001)

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3 min TRACE 171 time series

• TRACE oscillation amplitude ~3%

• FFT has 3 dominant periods ~(3, 5.9 & 7.3) mHz(330, 140 & 170) Seconds

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Conclusions

• Chromospheric/TR Acoustic Waves (Brynildsen, 2004)

• Waves propagate through chromosphere, TR and into the corona

• 3 min oscillations above sunspot umbra in the Chromosphere & TR where the umbral magnetic field is vertical

• Oscillations observed as 3 min propagations at TRACE temperatures where the field is more inclined.

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Acoustic Energy Flux

22

1332

64

I

I

m

TkN

kxtiVeV '

VV 2

2

1

• Assuming acoustic waves with velocity and pressure perturbations V' and P'

• The energy flux of the wave ε is given by:

kxtiPeP '

Assuming:• Optically thin emission →• Ideal gas• Complete ionisation of the plasma & Relative

abundances X=0.9 Y=0.1→

The energy flux of the wave is given by:

2I

eNN 91.0 pmm 29.1

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Acoustic Energy Flux

Log T (K) Log N (cm-3) ΔI/I ε (erg cm-2 s-1)

He I 4.5 10.959 0.02 28.3

O V 5.4 9.859 0.04 201.0

TRACE 171Å 6.0 9.259 0.03 225.6

O VDoyle (2003) derive Ne in sunspot plumes using O V diagnostic

TRACE 171Del Zanna (2003) derive Ne in the footpoints of quiescent coronal loops

He IEstimated Log Ne=11cm-3 for active regions

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Conclusion

• Acoustic waves propagate through chromosphere, TR and into the corona

• Acoustic waves are insufficient to heat active regions

• Technique may be used as a seismological tool to determine plasma properties ρ, T,…

• If ε constant through the atmosphere; may allow derivation of Ne at He I temperatures

• Need active region Ne measurement at He I temperatures