Exploration of the inner Heliosphere - what we have learned from Helios and what we want to study with Solar Orbiter 1st ISSI Team Meeting Bern, Feb 10-14, 2014 Program

Monday, 10 February

09:30 - 10:30 Welcome / Introductory Remarks (M. Falanga / W. Dröge)

10:30 - 11:15 HELIOS 1/2 particle observations (B. Heber)

11:15 - 11:45 Coffee Break

11:45 - 12:30 HELIOS magnetic field observations from 0.3 to 1 AU (R. Bruno)

12:30 - 14:00 Lunch Break

14:00 - 14:30 Detector simulation of the HELIOS E6 instrument (J. Marquardt)

14:30 - 15:15 Results from the STEREO mission (R. Gomez-Herrero)

15:15 -15:45 Pitch-angle dependent transport of particles through discontinuities (J. Kartavykh)

15:45 - 16:30 Particle acceleration and transport theory (R. Schlickeiser)

16:30 - 17:00 Discussion

17:00 Refreshments offered by ISSI Tuesday, 11 Feb

09:30 - 10:00 Particle-in-cell simulations of coronal shocks (A. Kempf

10:00 - 10:45 Solar Energetic Particle events at 0.3 AU (D. Lario)

10:45 - 11:15 Coffee Break

11:15 - 12:00 Shock acceleration theory / BepiColombo particle measurements (R. Vainio)

12.00 - 12:45 Solar Orbiter science goals and detector development (Bob Wimmer)

12:45 - 14:00 Lunch

14:00 - 14:30 Transport coefficient ratios and charge sign dependence (T. Antecki)

14:30 - 15:15 Observation of the Hohmann-Parker effect on SOHO, MSL, and Solar Orbiter (A. Posner)

15:15 - 16:00 Multi-point analysis of magnetic field data and turbulence theory (R. Wicks)

16:00 - 16:30 Coffee Break and Conference Photo

16:30 - 17:15 Solar radio, X-ray, and gamma-ray observations and theory (K.-L. Klein)

17:15 - 18:00 General discussion and suggestions for joint session on Wednesday

20:00 Team Dinner (Il Grissino) Wednesday, 12 Feb

Joint session with the Team of Gaetano Zimbardo and Horst Fichtner about "Superdiffusive transport in space plasmas and its influence on energetic particle acceleration and propagation"

09:45 - 10:45 Introduction to anomalous diffusion of energetic particles in space plasmas (G. Zimbardo) 10:45 - 11:15 Coffee Break 11:15 - 12:00 Highlights on fusion plasmas (I. Furno) 12:00 - 13:00 Transport modeling of multi-spacecraft particle events / Identification of transport modes and parameters (W. Dröge)

13:00 - 14:15 Lunch Break

14:15 - 14:35 Helios magnetic field observations and turbulence theory (R. Bruno) 14:35 - 15:10 How to simultaneously understand flux dropouts and fast perpendicular transport (R. Vainio) 15:10 - 15:40 The Diffusion Approximation vs. the Telegraph Equation for SEPs (F. Effenberger) 15:40 - 16:40 Non-diffusive Energetic Particle Transport in Intermittent Turbulence and at Shocks in the Heliosphere (J. le Roux) 16:40 - 17:10 Coffee Break 17:10 - 17:30 Particle Orbit Simulations (S. Dalla) 17:30 - 18:00 Wind magnetic field observations and turbulence theory (R. Weeks) Thursday, 13 Feb

10:00 - 12:45 General discussion, open questions, brainstorming, plans for joint publications, collaboration with team on superdiffusive transport

12:45 – 14:15 Lunch

14:15 – 17:00 Continuation of general discussion, analysis of specific data and events, planning of next meeting, assignment of tasks

Friday, February 14, 2014

Continuation of general discussion, splinter meetings, teleconference about particle observations on MAVEN Particle and fields missions in the inner (≲ 1 AU) Heliosphere

Mariner 10 (1973): exploration of Mercury, several fly-bys

Helios-1/2, IMP-8, ISEE-3: 1-axis stabilized , good directional information particle observations mostly at higher energies (≥ 1 MeV) , limited time resolution magnetic field and plasma observations X-ray, gamma-ray (SMM , 1980) and radio observations with low angular resolution still IMP-8, already Ulysses (Oct 1990) … Wind (Nov 1994) : excellent particle, plasma, magnetic field, radio observations no high-energy electron (> 0.5 MeV) and ion (> 5 MeV/n) data SOHO (Dec 1995): 3-axis stabilized, high energy particles, optical observations

ACE (Aug 1997) : 1-axis stabilized (Sun), particle (composition,isotopes, charge states), plasma, magnetic field measurements RHESSI (Feb 2002): image solar flares in energetic photons from soft X rays (~3 keV) to gamma rays (up to ~20 MeV) MESSENGER (2004): exploration of Mercury, limited solar particle observations STEREO (Dec 2006): two identical s/c, 3-axis stabilized, particle,plasma, optical and radio observations

Bepi Colombo (2016): exploration of Mercury, limited solar particle observations Solar Orbiter (2017) : 3-axis stab. particle, field, remote sensing observations Solar Probe + (> 2018) : 3-axis stab. particle, field, remote sensing observations PAST INTERPLANETARY MISSIONS HELIOS 1 & 2

Operational: 1974-12-10 until ~ 1980 (H1) 1976-01-15 until ~ 1986 (H2) Key results: • Multi-spacecraft observations 0.29 - 1.0 AU • 3He-rich events • Radial and longitudinal gradients of SEPs • Pitch-angle dependent transport • Evidence for lateral transport (diffusion perp to B)

Wibberenz & Cane 2006

electrons in the MeV range • high-energy proton measurements can be detected more than • spectra up to 1 GeV 80° from the flare longitude • angular distributions PAST INTERPLANETARY MISSIONS : ISEE - 3 / ICE

Launch Date: 1978-08-12 Key results: • high-energy electrons and protons from solar flares • protons and electrons from decay of solar neutrons • Jovian electrons, shock events, modulation, …

• electron spectra of impulsive and gradual flares exhibit single- and double power laws in momentum, respectively • spectra combined from Helios / ISEE-3 fit together well in spite of large angular separation

• solar system geometry on 1982 June 3 flare • flare protons are initially confined to field lines far from Earth, while neutrons cross field lines until they decay (Evenson et al, 1990) • neutron decay electrons on 1980 June 21 (Dröge et al, 1995) reconstruction of electron spectra from multi-spacecraft observations

3 April 1979 01:11 UT S25 W14

ISEE-3 r=1.0 AU N04 W63 Helios 1 r=0.75 AU S05 E14 Helios 2 r=0.68 AU S07 E14

spectral shapes similar on widely separated spacecraft injection from a relatively small source transport only weakly dependent on energy

characteristics of solar flare electron spectra plot (N(E), J(E) vs. E, p

flux spectra multiplied by power laws in

energy (open symbols) momentum (filled symbols)

Helios – 1/2 electron, proton, Helium observations during a large interplanetary particle event on 1 Jan 1978 attempts to reconstruct Helios electron fluxes from puls-height data and detector simulations power spectra Pzz (k) at various time periods before and after shock passage

comparison of Helios shock events with predictions from diffusive shock acceleration theory didn‘t work so well … energetic particles in the Heliosphere classical picture: e.g., Reames (1999)

(1) impulsive events localized source (flare) electron-rich (2) 3He-rich

(2) gradual events extended source (shock / CME) high ion flux high e/p ratio

(1) realistic transport models required to reconstruct particle focus here on particles properties at the Sun from spacecraft observations: from impulsive events acceleration time scales, energy and charge spectra, avoids complications relation to electromagnetic emission close to the Sun due to CMEs and (radio, X-ray, gamma-ray) interplanetary shocks SOLAR PARTICLE PROPAGATION (in a more or less undisturbed solar wind)

COMBINATION OF:

AZIMUTHAL TRANSPORT CLOSE TO THE SUN (CORONAL DIFFUSION) TRANSPORT PARALLEL TO B PITCH ANGLE SCATTERING, FOCUSING ADIABATIC ENERGY LOSSES FOR LOW-ENERGY (< 1 MeV/n) IONS CO-ROTATION DUE TO E x B drift POSSIBLE DIFFUSION ACROSS THE AVERAGE MAGNETIC FIELD transport parallel to the average magnetic field

fits spatial diffusion

parallel mean free path

5 Dec 1997 107 keV electrons Wind 3DP PI: R.P.Lin

focused transport transport equation for gyro-averaged phase space density f (z,m,|p|,t ), includes effects of pitch-angle (m = cos q) scattering and focusing (motion parallel to magnetic field) observational input to distinguish between different theories I : rigidity dependence of mfps

Palmer (1982) Dröge (2000)

“consensus range“ flat between 1–10 AU increasing towards electrons l|| between 0.08 and 0.3 AU lower rigidities increasing towards higher rigidities ions for mfps 0.02 – 2 AU lateral transport of solar energetic particles

coronal transport transport perpendicular to average magnetic field

diffusion across B field line random walk

QLT + FLRW K / K || ~ 0.02 – 0.05 needed for modulation of GCRs (Ferreira 2002)

CIR particle events K / K || ~ 1 (Dwyer et al 1997) Wind 3DP SST

ACE EPAM

STEREO SEPT transport modeling of STEREO-A/B and ACE electron observations on 7 Feb 2010: 2b. combination of extended injection at the Sun and 3-D interplanetary tranport

const/exp injection and classical backmapping of connecting field line (VSW around onset) from Dröge et al (2014) VSW = 413 km/s (3 s/c average) 2 l|| = 0.1 / cos (y) AU 2 2 0.5 l = 0.08 * l|| * (r/1 AU) * cos(y) * (1-m ) scales with gyroradius (B and sin(q))

STB ACE STA -16.4° 67.0° 104.4° information about the interaction of energetic particles with magnetic turbulence in the solar wind can be obtained from spectral densities of the fluctuations:

observations of magnetic fluctuations consistent with ~ X % slab content ~ Y % 2-D content Denskat, Beinroth and Neubauer, 1983 J. Geophys. 54, 60

HELIOS high-resolution ( > 1 vec/s) magnetic field data available now ? Figure courtesy alternative turbulence models: of T. Horbury anisotropy of energy transfer – critical balance

Goldreich & Sridhar (1995)

• critical balance region close to k|| • results in hydrodynamic-like caskade

in wedge of wave vectors near k|| ~ 0 • expect Kolmogorov scaling inside this region reduced power spectrum in inertial range P(f, qB ) exhibits -5/3 f behaviour at qB near 90

-2 f behaviour at small qB

Chen et al. 2011 Figure from T. Horbury CURRENT INTERPLANETARY MISSIONS : Messenger

Messenger - Launch date: 2004-08-03 - Mercury fly-bys: 2008-01-14 / 2008-10-06 / 2009-09-29 - Mercury orbit insertion: 2011-03-18 - exploring the inner Heliosphere (0.3 – 0.7 AU) from now to 2012 Energetic Particle Spectrometer (EPS) ions: 30 keV – 2.7 MeV electrons: 30 keV – 1 MeV

multi-spacecraft observations of an energetic Electron Event from 0.3 to 1.0 AU: ACE, MESSENGER, and STEREO A/B

ACE News #139 - June 13, 2011 George C. Ho, JHUAPL FUTURE INTERPLANETARY MISSIONS : Solar Orbiter

Solar Orbiter Launch date: 2017 Elliptical orbit 0.23 – 0.29 AU (perihelion) 0.75 – 1.2 AU (aphelion) Key objective: Explore how the Sun creates and controls the Heliosphere Science questions: • How and where do the solar wind plasma and magnetic field originate in the corona? • How do solar transients drive heliospheric variability? • How do solar eruptions produce energetic particle radiation that fills the heliosphere? • How does the solar dynamo work and drive connections between the Sun and the heliosphere?

SEP measurements: ions: ~ 0.1 – 100 MeV/n electrons: ~ 50 keV – 20 MeV

slide courtesy by R. Marsden / ESA FUTURE INTERPLANETARY MISSIONS : Solar Orbiter

Understanding release and transport mechanisms requires going close to the Sun

slide courtesy by R. Marsden / ESA FUTURE INTERPLANETARY MISSIONS : Bepi Colombo

Bepi Colombo - Launch date: 2016 - Mercury arrival: 2023

- Mercury Planetary Orbiter (MPO): Solar Intensity X-ray & particle Spectrometer (SIXS)

- Primary objective: provide observations of solar X-ray and particle irradiation at Mercury’s surface in support of Mercury Imaging X-ray Spectrometer (MIXS)

- Secondary objective: monitoring of SEP fluxes and spectra protons: 1 – 4.3 MeV electrons: 0.1 – 0.3 MeV

slide courtesy by R. Marsden / ESA FUTURE INTERPLANETARY MISSIONS : Solar Probe Plus

slide courtesy by R. Marsden / ESA