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Element Abundances and the Source of the Slow Speed Solar Wind Martin Laming

Element Abundances and the Source of the Slow Speed Solar Wind Martin Laming. Naval Research Laboratory, Washington DC 20375.

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Element Abundances and the Source of the Slow Speed Solar Wind Martin Laming

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  1. Element Abundances and the Source of the Slow Speed Solar Wind Martin Laming Naval Research Laboratory, Washington DC 20375 Work supported by NASA Astrophysics Theory Program, NASA Heliospheric Physics Supporting Research Program, NASA Laboratory Analysis of Returned Samples Program, and Basic Research Funds of the Chief of Naval Research

  2. Elemental Fractionation • FIP Effect known (suspected) since Pottasch (1963, ApJ, 137, 945). • Now “understood” (Laming 2015, LRSP, 12, 2; also 2004, 2009, 2012) as due to action of ponderomotive force in chromosphere. • Most recent data from Reames 2018 Solar Phys. 293, 47 SEP data from Reames (2014)

  3. Plan of Talk • Introduction to FIP model and Ponderomotive Force • Results for Solar Closed Field • Application to Open Field and Solar Wind

  4. What is the Ponderomotive Force I? J. D. Barrow, "Much ado about nothing", (2005) Lecture at Gresham College. (Includes discussion of French naval analogy.) Wave modes unrestricted Net force Wave modes restricted by boundary conditions Wave modes unrestricted

  5. What is the Ponderomotive Force II? • (J + dJ) x (B + dB)  J x B + dJ x B +J x dB + dJ x dBgives partial origin of ponderomotive force; need to include other second order terms for complete description • Ponderomotive acceleration, for Wi >> w; a = ¼ c2 d(dE┴2/B2)/dz = ¼ d(dB┴2/4pr)/dz, is independent of ion mass m in magnetic plasma and independent of charge, but only acts on charged particles. • WKB approximation (no refraction/reflection), dB┴ goes asr1/4, so a ≈ -1/(2r)d(dB┴2/8p)/dz, (negative) gradient of magnetic pressure in wave.

  6. Ponderomotive Force Derivationsfz= ½ rc2∂(dE┴2/Bz2)/∂z • Lagrangian for particles + wave & energy partitioning in Alfvén waves (Laming 2009; 2015) • Single particle equations of motion in E & B fields (Lundin & Guglielmi 2006) • Polarization and magnetization produced by waves (Laming 2017) • Change in e produced by passage of Alfvén wave (Pitaevskiĭ 1961; Washimi & Karpman 1976)

  7. Plan of Talk • Introduction to FIP model and Ponderomotive Force • Results for Solar Closed Field • Application to Open Field and Solar Wind

  8. Chromospheric Structure 1000 km b≈1 1000 km Chromospheric model from Avrett & Loeser (2008) at each footpoint Force Free Magnetic Field (Athay1981)

  9. Chromospheric Non-thermal Velocities(Carlsson et al. 2015 ApJL, 809, L30; Carlsson et al. 2016, A&A, 585, A4, Heggland et al. 2011, ApJ, 743, 142)

  10. Ponderomotive Accelerationa= ½ c2∂(dE┴2/Bz2)/∂z = ½ ∂(dv┴2)/∂z Fractionation ~ expnna/[nn +ni(1/x-1)]vs2dz • =element ion fraction nn’ni=collision rates with background gas, usually nn<<ni a = ponderomotive acceleration vs2 = kT/mi + vmturb2/2 + vSM2/2 + vflow2 ; thermal speed + longitudinal turbulent, slow mode, and flow velocities Compute Alfvén propagation on closed loop or open field.

  11. Coronal Wave PatternsResonant Frequency is 0.106 rad s-1, B=30G in coronaa – Elsässer variable components, b – wave energy fluxes, c – ponderomotive acceleration a b c

  12. Chromospheric Footpoint (resonant)a – Temperature and density, b – low FIP ion fractions, c – high FIP ion fractions, d – wave actions, e - ponderomotive acc. and slow mode waves, f – FIP fractionation

  13. Correlation of non-thermal velocities with FIP fractionation… Figures from D. Baker et al. 2013, ApJ, 778, 69 Amplitudes of NT broadening more consistent with planar Alfvén waves than torsional Alfvén waves?

  14. He/H =0.052+/- 0.005 in the Solar CoronaLaming & Feldman (2001) ApJ, 546, 552Laming & Feldman (2003) ApJ, 591,1257 He II 1084.94 88”-118” off limb 243”-273” off limb Relative to N II 1083.98, 1084.58, and the blend of 1085.53/1085.55/1085.68 Å (all scattered light from the disk) He II 1084.94 is stronger at the lower altitude, indicating a true He II coronal emission component in.

  15. HERSCHEL I Results (Fineschi et al. 2010, Proc. ICSO Conf, Rhodes, Greece, Fineschi et al. 2014, COSPAR Conf. D2.4-0017-14, Moscow, Russia) HEIT and HECOR He II 304 HEIT He II, SCORE LyA and He II

  16. HERSCHEL I Results Lya intensity He/H abundance (normalized) See also Laming & Feldman (2001; 2003) He/H peaks at the streamer-CH boundaries for all heights (1.5, 1.7, 1.9, 2.1 Rs)

  17. Alfvén Waves have Coronal Origin: (Rakowski, C. E. & Laming J. M. 2012, ApJ, 754, 65Laming J. M. 2017, ApJ, 844, 153) • He/O depletion strongest for waves resonant with coronal loop w = npvA/L, longer loops, weaker B • Resonance only guaranteed with coronal origin  nanoflares • Would expect high coronal He abundance if solar wind depletion was due to inefficient Coulomb drag, since CMEs cannot explain excess He. B=5,10,15,20 G L=50, 75, 100 Mm Rakowski & Laming (2012)

  18. Hyperion SimulationsDahlburg, Laming,Taylor & Obenschain 2017, ApJ, 831, 1603D compressible MHD, footpoint motions stress magnetic field followed by episodic energy release in the corona

  19. Ponderomotive Acceleration and Coronal Temperature in Simulations (need ~104 m s-2)

  20. Plan of Talk • Introduction to FIP model and Ponderomotive Force • Results for Solar Closed Field • Application to Open Field and Solar Wind

  21. Closed/Open Field and Waves

  22. Coronal Hole Model (following Cranmer et al. 2007, ApJS, 171, 520) Wave Spectra in Transition Region Wave Amplitudes with Height r/Rʘ -1

  23. Coronal Hole Wave Patternsa – components of Elsässer variables, b – wave energy fluxes, c – ponderomotive acceleration a b c

  24. Fast/Slow Wind Fractionationtop: fast wind, coronal magnetic field 10Gbottom: slow wind, coronal magnetic field 30G

  25. Schmelz et al. (2012), Figure 1. Variation of S? Variation of S abundance: Low S/O  fractionation in background protons High S/O  fractionation in background neutral H Clue to solar wind origin?

  26. For Solar Orbiter (and Solar Probe Plus…) • Connection with Alfvén waves offers novel and unexpected diagnostics of wave motions in the chromosphere and corona. • Abundances should correlate with solar wind waves/turbulence. • Are slow wind and closed loop corona fractionations exactly the same? Behavior of S offers insight into slow solar wind origin. • Further connections with local helioseismology through wave physics in the outer solar atmosphere.

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