Generation of quasi-periodic pulsations in solar flares by MHD waves
Quasi-periodic upflows in the solar active region
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Quasi-periodic upflows in the solar active region Hui Tian High Altitude Observatory, National Center for Atmospheric Research ASP research review 2010/10/ 27
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Hui Tian High Altitude Observatory, National Center for Atmospheric Research. Quasi-periodic upflows in the solar active region. ASP research review. 2010/10/27 . Outline. The solar corona Propagating disturbances interpreted as waves - PowerPoint PPT Presentation
Transcript of Quasi-periodic upflows in the solar active region
Quasi-periodic upflows in the solar active region
Hui Tian High Altitude Observatory,
National Center for Atmospheric Research
ASP research review
2010/10/27
Outline
The solar coronaPropagating disturbances interpreted as
wavesCombination of imaging and
spectroscopic observationsOscillations driven by repetitive upflowsConclusion
The solar corona Extremely hot corona
• Heating problem• EUV & X-Ray emission
AIA/SDO 193 Å
Image Credit: SDOPeter, 2004, Reviews in Modern Astronomy
Highly inhomogeneous corona
Propagating disturbances interpreted as waves
De Moortel, 2002, Astronomy & Astrophysics
Propagating disturbances in imaging observation• Period: 3-30 minutes• Speed: 50-200 km/s• Interpreted as magneto-acoustic waves
Combination of imaging and spectroscopic observations (I)
XRT observation• 3-min cadence image
sequence• Relentless upflows at
the boundary of the AR
Combination of imaging and spectroscopic observations (II)
EIS observation• 32-s cadence SAS spectra• Several emission lines
Fe XII 195.12 Å Fe XIII 202.04 Å
Single Gaussian fit• Intensity• Doppler shift• Line width
R-B
Combination of imaging and spectroscopic observations (III)
Oscillations driven by repetitive upflows (I)
Oscillations driven by repetitive upflows (II)
Oscillations driven by repetitive upflows (III)
black: intensity red: Doppler shift (inverted) green: line width purple: R-B (inverted) blue: relative intensity of the 2nd component cyan: relative Doppler shift of the two components
Oscillations driven by repetitive upflows (IV)
Doppler shift & R-B are inverted in time series
Conclusion Coronal oscillations could be signatures of
• Waves• Repetitive upflows
Spectroscopic observations could distinguish between the two phenomena• Waves: double frequency of line width; excess blueward
and redward emission alternatively• Upflows: same frequency of intensity, Doppler shift,
and line width; repetitive excess blueward emissionThe upflows could be the result of impulsive
heating at the lower layers and may be an efficient way to provide the corona with hot plasma
Reference: Tian et al., ApJ, 727, L37, 2011
Thank you!
