Thermal, Nonthermal, and Total Flare Energies

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Thermal, Nonthermal, and Total Flare Energies

• Brian R. Dennis
• RHESSI Workshop
• Locarno, Switzerland
• 8 11 June, 2005

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Separating Thermal Nonthermal

• Temporal - gradual vs. impulsive
• Spatial - coronal vs. footpoint
• Spectral - exponential vs. power-law
• Spectral iron-line complexes - always
  thermal!!!?

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Difficulties with Continuum
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26 April 2003 Flare Time Profile
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RHESSI Count-rate Spectrum
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Flux ratio vs. Temperature(Caspi Lin, 2005)
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Emissivity vs. Temperature (Caspi Lin, 2005)
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Fe-line Equivalent Width26 April 2003
CHIANTICoronal Abundances
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Ionization Fraction
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Conclusions

• Fe Fe/Ni complexes are real.
• Fe centroid energies vary with T count rate.
• Fe to Fe/Ni ratio varies with T.
• Different dependency for different flares.
• Fe equivalent width varies with T
• Data in A1 attenuator state most reliable.
• Up to 50 less FeXXV than Mazzotta et al. predict
  (Phillips).
• Eagerly await XSM spectra for comparison.

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Flare vs. CME Energy

• Flare thermal energies
• SXR-emitting plasma (GOES RHESSI)
• Radiated energy (GOES)
• Conducted energy (GOES RHESSI)
• Total Solar Irradiance increase (SORCE)
• Flare nonthermal energies
• Electrons from HXRs (Holman)
• Ions from gamma-rays (Share)
• CME kinetic energy
• (LASCO Gopalswamy)

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Thermal Plasma

• The thermal energy content of the thermal plasma
• Uth 3 ne V kT 3 k T EM f Vapparent1/2 erg
• f is the filling factor (assumed to be 1)
• Emission measures (EM) and temperatures (T)
  obtained from both RHESSI and GOES soft X-ray
  observations.
• The source volumes (V) were obtained from RHESSI
  12 25 keV images
• V f Vapparent f A3/2
• A is the area inside the contour at 50 of the
  peak value.

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Figure 1. RHESSI image at the impulsive peak of
the 2 Nov. 2003 flare.Contours blue 12 25
keV (50), magenta 50 100 keV (30 70)
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Radiated Energy

• The energy radiated from the thermal plasma over
  all wavelengths
• Lrad EM frad(T) ergs s-1
• frad(T) is the Chianti radiative loss function
  assuming coronal abundances.
• Total radiated energy from the flare plasma
• Ltotal n Lrad(t) Dt erg
• where the sum is over the duration of the SXR
  flare.

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Figure 2. Radiative losses vs. plasma
temperature.
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Conductive Cooling

• The conductive losses Lcond were estimated
  assuming classical conduction
• Lcond A k0 T5/2 VT ? 4 A/l k0 T7/2 erg s-1
• where k0 10-6 erg cm-1 s-1 K-7/2 the
  classical Spitzer coefficient
• A is the loop cross-sectional area in cm2
• l is the loop half length.
• A, l, and T can be determined from RHESSI images.
• However, since there is so much uncertainty in
  estimating this cooling component, no values are
  included in this analysis.

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X8.3 flare 2 Nov. 2003GOESSXRData
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X8.3 flare 2 Nov. 2003GOESSXRData
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Conclusions

• Flare and CME energies are correlated for the
  Oct/Nov 2003 period.
• Total Flare and CME energies comparable to within
  a factor of 10.
• Peak energy in SXR-emitting plasma is only 1 of
  total flare energy in some cases.
• Energy radiated by SXR-emitting plasma is only
  10 of total flare energy in some cases.
• Energy in nonthermal electrons and ions can be a
  large fraction of the total flare energy.
• Dominant flare energy in impulsive phase may be
  electrons and/or ions leading to early peak in
  total solar irradiance increase seen with
  SORCE/TIM.
• Some of the measured radiant energy of flare may
  result from a decrease in the opacity of the
  lower chromosphere caused by a decrease in the H
  concentration (Fontenla, private communication).

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