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Heavy Ion Charge States in Solar Energetic Particle Events

Heavy Ion Charge States in Solar Energetic Particle Events. Berndt Klecker Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany Workshop on Solar Terrestrial Interactions from Microscale to Global Models Sinaia, Romania, September 6 - 10, 2005. OUTLINE.

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Heavy Ion Charge States in Solar Energetic Particle Events

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  1. Heavy Ion Charge States in Solar Energetic Particle Events Berndt Klecker Max-Planck-Institut für extraterrestrische Physik, 85741 Garching, Germany Workshop on Solar Terrestrial Interactions from Microscale to Global Models Sinaia, Romania, September 6 - 10, 2005

  2. OUTLINE • Introduction • Measurement Techniques • Ionic Charge State (Fe , Ne, Mg, Si) in IP Shock /CME Related SEP Events • Ionic Charge States (Fe, Ne, Mg, Si) in 3He-rich and Heavy Ion-rich Events • The Energy Dependence of Ionic Charge States - Mechanisms • Summary

  3. ENEGETIC PARTICLES IN THE HELIOSPHERE

  4. INTRODUCTIONWhy are Ionic Charge States Important? • Information on the Source • i.e. Solar (Solar Wind, Corona); Interstellar, e.g. He+ Pickup Ions • For Solar Source: Source Location (Temperature, Density) • Important Information on Fractionation, Acceleration and Propagation • Processes • Injection, Acceleration and Propagation generally depend on Rigidity, • i.e. particle velocity v and M/Q

  5. WHERE DO SOLAR ENERGETIC PARTICLES COME FROM ?The Historical Development Phase 1: Everything comes from Flares Phase 2: ~ 70s to 90s Flares and CMEs / Shocks Impulsive and Gradual SEPs Phase 3: Present Flares and CMEs / Shocks Relative Contribution to SEPs under Debate Classification of 2 distinct types of SEPs events in question. 1st measurement of 2 GLEs in 1942 Forbush, 1946 Lin, 1970; Pallavicini et al., 1977, Reames 1999

  6. IMPULSIVE EVENTS Average Elemental Abundances NEW • Mason et al., 2002, 2004 • Reames, 1999 Average of 20 Events Energy: 385 keV/nuc

  7. EARLY RESULTS for Large (gradual) IP-Shock Related SEP Events • Results from early measurements at ~1 Mev/nuc: • Qm(Fe) ~12 -16 • -> Te ~ 1.5-2 106 K • Coronal Temperatures • Q ~ Solar Wind, but somewhat larger (Fe) Gloeckler et. al., 1976, Hovestadt et al. 1981, Luhn et al., 1984

  8. EARLY RESULTS for 3He-, Fe-rich (Impulsive) SEP Events Qm (Fe) ~ 19-20, Qm (Si) ~14 -> Te ~107 K Klecker et al., 1984, Luhn et al., 1987

  9. EARLY RESULTS Puzzle: Gradual: Q at ~1 MeV/n similar to Solar Wind, but for some ions (e.g. Fe) higher than in Solar Wind Impulsive: Si fully ionized, i.e. M/Q=2 How can abundances be enhanced relative to C or O (M/Q=2 for C - Si) Question: Measurement only in small energy range at ~1MeV/nuc. How is Q at other energies?

  10. IONIC CHARGE DETERMINATIONMeasurement Techniques In-Situ Measurement (e.g. by Electrostatic Deflection) Energy range from Solar Wind energies to a few MeV/amu Advantage: Direct Measurement of E, M, Q, Q Distribution, Energy Dependence Q (E) Measurement of the Rigidity Cutoff in the Earth’s Magnetic Field Measurement of M, E, Rcutoff > Determination of average Q Advantage: Q Determination to High Energies of 10s of MeV/amu Indirect Methods using information on Energy Spectra, Composition, or time- intensity profiles Disadvantage: Model dependent

  11. IONIC CHARGE DETERMINATION(1) In-Situ Measurements We want: E, M, Q Measurement of E/Q (electrostatic defl.) E/M (e.g. time-of-flight) E (SSD) Solar Wind: SWICS / Ulysses, SWICS/ACE, CTOF/SOHO Suprathermal: STOF /SOHO, SEPICA/ACE ~ 0.2 - 0.6 Mev/nuc: SEPICA/ACE ~ 0.5 - 2.0 Mev/nuc: IMP-7/8, ISEE-1/3

  12. IONIC CHARGE DETERMINATIONMeasurement Techniques In-Situ Measurement (e.g. by Electrostatic Deflection) Energy range from Solar Wind energies to a few MeV/amu Advantage: Direct Measurement of E, M, Q, Q Distribution, Energy Dependence Q (E) Measurement of the Rigidity Cutoff in the Earth’s Magnetic Field Measurement of M, E, Rcutoff > Determination of average Q Advantage: Q Determination to High Energies of 10s of MeV/amu Indirect Methods using information e.g. on Energy Spectra, Composition, or time- intensity profiles Disadvantage: Model dependent

  13. IONIC CHARGE DETERMINATION(2) Rigidity Cutoff of the Earth’s Magnetic Field SAMPEX (polar Orbit, ~ 600 km altitude) • Determine lc(Rc) with ions of known charge (H+) on an orbit-by orbit bases • Determine lc for other ions • Compute Qavg from Rc, lc and E, M Advantage: Large Energy Range Energy Dependence Disadvantage: Intensity needs to be large Mason et al., 1995; Mazur et al., 1995; Leske et al., 1995; Oetliker et al., 1997

  14. IONIC CHARGE DETERMINATION(2) Rigidity Cutoff Variations During SEP Events SAMPEX • lc(Rc) can vary by several degrees • during an event • Determine lc for H+ or He2+ on an orbit by • orbit basis • Compute adjusted lc from time variation • Use lc(Rc) or linear fit: cos4(lc) = a Rc+b • to derive Qavg from Rc, lc and v, M Qavg = (M v) / (Rc e) Leske et al., 2001

  15. IONIC CHARGE DETERMINATIONMeasurement Techniques • Indirect Methods using information e.g. on Energy Spectra, Composition, or time - intensity profiles • Disadvantage: Model dependent • Energy Spectra: M/Q dependent roll-over of spectra (Tylka et al., 2000) • Composition: M/Q-dependent fractionation effects (Cohen et al., 1999) Rigidity dependent interplanetary propagation: • Time to maximum intensity (O’Gallagher et al, 1976, Dietrich & Tylka, 2003) • SEP decay phase (Sollitt et al., 2003)

  16. IONIC CHARGE DETERMINATION(3) Indirect Methods April 20-24, 1998 Tylka et al., 2000 FeX(E) ~ E-g exp(-E/E0X) E0X =E0H*(Q/M)a, a ~1 • Determine E0X, g from spectral fit • Determine M/Q from (2)

  17. IONIC CHARGE DETERMINATIONExperiments and Energy Range EEARLY MEASUREMENTS FROM IMP-7 / 8, ISEE - 1/3 RECENT MEASUREMENTS FROM SAMPEX - SOHO - ACE

  18. NEW RESULTS (SAMPEX-SOHO-ACE)Gradual Events:Mean Ionic Charge Varies With Energy Systematic Increase of Q with Energy above ~10 MeV/amu, in particular for Fe Oct. 1992 SAMPEX: Mason et al., 1995; Leske et al., 1995, Oetliker et al., 1997)

  19. NEW RESULTS (SAMPEX-SOHO-ACE)Gradual Events:Large Variability of Q (E) Large Variability of Q (E) for Heavy Ions, in particular for Fe Day 121, 1998 CME / IP Shock Event At low energies of up to ~ 250 keV/amu: Q similar to Solar Wind 0.01 - 0.1 MeV/n At energies above ~200 keV/nuc: Large Variability QFe(E) increasing at E > 10 Mev/nuc - often QFe (E) increasing at ~ 1 MeV/nuc - some cases SW: 10.1 Möbius et al., 1999, 2000, 2003; Bogdanov et al., 2000, Klecker et al. 2000, 2001, 2003; Popecki et al., 2000, 2001, 2003; Bamert et al., 2002; Labrador et al., 2003

  20. NEW RESULTS (SAMPEX-SOHO-ACE)Gradual Events:Mean Ionic Charge Varies With Energy SAMPEX Results Mason et al., 1995; Leske et al. 1995; Oetliker et. 1997; Mazur et al., 1999; Leske et al., 2001; Labrador et al., 2003 ACE Results Möbius et al., 1999, 2000, 2003; Bogdanov et al., 2000, Klecker et al. 2000, 2001, 2003; Popecki et al., 2000, 2001, 2003

  21. NEW RESULTS (ACE+SOHO)ImpulsiveEvents:Mean Ionic Charge Increases ALWAYS with Energy Möbius et al., 2003; Klecker et al, 2005

  22. IMPULSIVE EVENTS Ionic Charge of Ne, Mg, Si, Fe (ACE)

  23. THE ENERGY DEPENDENCE OF THE IONIC CHARGE Overview of Possible Mechanisms Ionization by e, p in a dense plasma in the low corona “Stripping Model” Effect of Energy Spectra with M/Q-dependent roll-over (i.e. Acceleration and Propagation effects) Mixing of 2 Sources: Solar Wind Origin and Flare Origin (i.e Heavy Ion Rich)

  24. Comparison of Ionic Charge States with Stripping ModelI. The Equilibrium Case The Equilibrium Case Impact ionization by p + e Radiative + dielectronic recombination Qm at E < 0.1 MeV/amu depends on Te (electron distribution function) Large Increase of Qm at E > 0.1 MeV/n by (p+e) impact ionization Cross sections and rate coefficients: Arnaud & Raymond, 1992, Mazzotta et al., 1998; Kovaltsov et al. 2001 Electrons: Maxwell distribution Klecker et al., 2005 Ostryakov et al., 1999; Barghouty & Mewaldt, 1999; Kocharov et al., 2000

  25. Comparison of Ionic Charge States with Stripping ModelII. The Non-Equilibrium Case Q 24 20 16 12 8 The Non-Equilibrium Case Impact ionization by p + e Radiative + dielectronic recombination Qm depends on N*t Equilibrium will be reached for N * t ~ 1-10 * 1010 cm-3 s (for E ~ 0.1 - 10 MeV/n) Equilibrium N*t is energy dependent Kocharov et al., 2000

  26. Comparison of Fe Ionic Charge State Datawith Stripping Model Klecker et al., 2005 The Equilibrium Case Qm at E < 0.1 MeV/n consistent with Te 1.2 - 1.4 106 K Large Increase of Qm at E > 0.1 MeV/n N * t ~ 1 * 1010 cm-3 s t ~ 1 - 100 s: N ~ 108 - 1010 cm-3 -> Acceleration low in Corona Increase of Qm with E larger than in equilibrium stripping model What is missing?

  27. INTERPLANETARY TRANSPORTINCLUDING THE EFFECTS OF ADIABATIC DECELERATION DIFFUSION CONVECTION SOURCE Energy Loss by Adiabatic Deceleration 1/E dE/dt = 4/3 Vsw / r s-1 Integrated (0.01 AU -> 1AU) energy loss depends on scattering mean free path l and particle velocity. Model, including accelerationKartavykh et al., 2005

  28. A MODEL FOR ACCELERATION AND TRANSPORT Acceleration Model, including At the Sun: Spatial and Momentum Diffusion, Ionization, Coulomb Losses Interplanetary Space: Transport, including Spatial Diffusion, Convection, Adiabatic Deceleration. Simultaneous fit of: Energy Spectra Intensity-time profile QFe (E) (Kartavykh et al., 2004, 2005)

  29. MODEL FITS FOR Ne, Mg, Si and Fe July 20, 1999 Event July 3, 1999 Event

  30. THE ENERGY DEPENDENCE OF THE IONIC CHARGE 2. Effect of Energy Spectra with M/Q-dependent Roll-Over Klecker et al, 2001 Fe Mean Ionic Charge computed with sample SW-Fe ionic charge distribution

  31. THE ENERGY DEPENDENCE OF THE IONIC CHARGE 3. Mixing of 2 Populations Tylka et al. 2001 MixingSWwith QFe> 16+ from Impulsive Events

  32. SUMMARY-1Impulsive Events • All non Interplanetary Shock related 3He-rich, Fe-rich events investigated so • far show • Qm (Fe) ~11 - 13 at 10 - 100 keV/n with a steep increase of Qm (Fe) to • Qm (Fe) ~14 - 20 in the energy range 180 - 550 keV/n. • For several events, the increase above ~200 keV/n is steeper than expected for • charge stripping equilibrium conditions. Interplanetary transport effects • (adiabatic deceleration) are important and can explain the steeper increase. • Homogeneous models provide good fits, if Q(E) is not too steep • Inhomogeneous models are required to explain observations of steeper charge • spectra

  33. SUMMARY-2 • The steep increase of Q with E for E < 1 MeV/nuc requires acceleration low • in the corona • N * tA ~ 1-10 * 1010 cm-3 s • For tA ~ 10-100 s this corresponds to N ~ 108-1010 cm-3, i.e. altitudes < 2 Rs • High Charge States (e.g. Fe+20) observed at energies of ~ 1 MeV/n • can be used as Tracer for a Source Low in the Corona

  34. SUMMARY-3Gradual Events • High Charge States (and abundance enhancements) of Fe at Energies of • ~ 1 MeV/nuc • Acceleration low in the corona • High Charge States (and abundance enhancements) of Fe at Energies • > 10 MeV/nuc • Option 1: Injection and acceleration in the contemporary flare • Option 2: Injection and acceleration of 2 components by CME driven • coronal shock • (1) ~ solar composition, SW charge states • (2) ‘flare’ composition (heavy ion rich, high charge states)

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