In this section we describe detailed lower-level objectives of each of the four top science objectives.
- Objective 1: What drives the solar wind and where does the heliospheric magnetic field originate?
- 1.1 What are the source regions of the solar wind and heliospheric magnetic field?
- 1.1.1 Source regions of the fast solar wind
- 1.1.2 Source regions of the slow solar wind
- 1.1.2.1 Does slow wind originate from the over-expanded edges of coronal holes?
- 1.1.2.2 Does slow and intermediate solar wind originate from coronal loops outside of coronal holes?
- 1.1.2.3 Abundance of minor ions as a function of height in the corona as indicator of slow or fast wind
- 1.1.2.4 Study of density fluctuations in the extended corona as a function of the outflow velocity of the solar wind while evolving in the heliosphere
- 1.1.2.5 Structure and evolution of streamers
- 1.1.2.6 Disentangle the spatial and temporal variability of the slow wind
- 1.1.2.7 Trace streamer blobs and other structures through the outer corona and the heliosphere.
- 1.1.2.8 Determine the velocity, acceleration profile and the mass of the transient slow wind flows
- 1.1.3 Source regions of the heliospheric magnetic field
- 1.1.4 Transverse themes
- 1.1.4.1 Reconnection
- 1.1.4.1.1 Interchange reconnection between open and closed field lines and its role in slow wind generation
- 1.1.4.1.2 Identify coronal reconnection sites by measuring impulsive event material
- 1.1.4.1.3 Identify reconnection exhausts in the solar wind
- 1.1.4.1.4 Current sheets inferred by determining the magnetic field geometries at local chromospheric heating sites
- 1.1.4.1.5 Identify and characterise the solar wind reconnection physics in current sheets with thickness down to the ion scales and smaller
- 1.1.4.1.6 Photospheric reconnection
- 1.1.4.1.7 Electron acceleration in coronal reconnection regions
- 1.1.4.1.8 Formation of flux ropes/CMEs via magnetic reconnection in the corona
- 1.1.4.1 Reconnection
- 1.2 What mechanisms heat the corona and heat and accelerate the solar wind?
- 1.2.1 What mechanisms heat the corona?
- 1.2.1.1 Energy flux in the lower atmosphere
- 1.2.1.2 Energy and mass flux in the corona.
- 1.2.1.3 Contribution of flare-like events on all scales
- 1.2.1.4 Observe and explore flare-like ‘heating events’ from the quiet corona
- 1.2.1.5 Determine whether coronal heating is spatially localized or uniform, and time steady or transient or impulsive for a wide range of magnetic loops with different spatial scales.
- 1.2.1.6 Resolve the geometry of fine elemental loop strands
- 1.2.1.7 Detect and characterise waves in closed and open structures
- 1.2.1.8 Investigate the role of small scale magnetic flux emergence in energizing the above laying layers
- 1.2.1.9 Multi-temperature diagnostics of flaring coronal loops
- 1.2.1.10 Heating in flaring loops vs heating in active regions
- 1.2.2 What mechanisms heat and accelerate the solar wind?
- 1.2.2.1 Determine where energy is deposited in the solar wind
- 1.2.2.2 What drives the evolution of the solar wind distribution functions in situ?
- 1.2.2.3 What is the nature and origin of waves, turbulence and small-scale structures?
- 1.2.2.4 Solar wind reconnection physics
- 1.2.2.5 Magnetic reconnection in the chromosphere, the transition region and the corona
- 1.2.2.6 Study fast plasma flows from the edges of solar active regions discovered with Hinode/EIS
- 1.2.2.7 Study the correlation degree between velocity and magnetic field fluctuations in the interplanetary space
- 1.2.2.8 What determines the azimuthal flow of the near-Sun solar wind?
- 1.2.1 What mechanisms heat the corona?
- 1.3 What are the sources of solar wind turbulence and how does it evolve?
- 1.1 What are the source regions of the solar wind and heliospheric magnetic field?
- Objective 2: How do solar transients drive heliospheric variability?
- 2.1 How do CMEs evolve through the corona and inner heliosphere?
- 2.2 How do CMEs contribute to solar magnetic flux and helicity balance?
- 2.3 How and where do shocks form in the corona and in the heliosphere?
- 2.3.1 Coronal shocks
- 2.3.2 What are the properties and distribution of heliospheric shocks?
- 2.3.2.1 Understand coronal conditions under which the shocks form and determine the interplanetary conditions where they evolve
- 2.3.2.2 Identify interplanetary shocks and characterise their spatial and temporal evolution
- 2.3.2.3 Study heating and dissipation mechanisms at shocks with radial distance
- 2.3.2.4 Identify mechanisms that heat the thermal solar wind particle populations near shocks and determine their energy partition
- 2.3.3 Resolve the interplanetary shock field and plasma structure down to the spatial and temporal scales comparable and smaller than the typical ion scales.
- 2.3.4 Shock-surfing acceleration mechanism
- 2.3.5 Understand the radio emissions from the ICME driven shocks
- 2.3.6 Identify shock accelerated particles
- Objective 3: How do solar eruptions produce energetic particle radiation that fills the heliosphere?
- 3.1 How and where are energetic particles accelerated at the Sun?
- 3.1.0 Explore in depth the SEP properties
- 3.1.1 CME and shock associated SEP sources
- 3.1.1.1 Where and when are shocks most efficient in accelerating particles?
- 3.1.1.2 Why are gradual SEP events so variable?
- 3.1.1.3 How are superhalo particles accelerated continuously in the corona and solar wind?
- 3.1.1.4 How can SEPs be accelerated to high energies so rapidly?
- 3.1.1.5 Do proton-amplified Alfvén waves play a role in accelerating particles at shocks?
- 3.1.1.6 What causes SEPs' spectral breaks?
- 3.1.1.7 Are there favourable environments for particle acceleration?
- 3.1.2 SEPs associated with flares, coronal loops and reconnection regions
- 3.1.2.0 Impulsive SEP event sources
- 3.1.2.1 Understand energy release and particle acceleration process
- 3.1.2.2 Evaluate how significantly large flares contribute directly to gradual SEP events
- 3.1.2.3 Flare seed particles
- 3.1.2.4 Explore the fact that only some of the hard X-ray peaks are related to escaping electrons, while others are not
- 3.1.2.5 X-ray prompt events
- 3.1.2.6 Delayed events (between X-ray peak and electron release time)
- 3.1.2.7 How are so many electrons accelerated on such short time scales to explain the observed hard X-ray fluxes?
- 3.1.2.8 Explore the type III radio bursts delays
- 3.1.3 Relativistic electron acceleration
- 3.1.4 Other high sensitivity X-ray studies
- 3.2 How are energetic particles released from their sources and distribute in space and time?
- 3.2.0 What controls the escape of the particles to the heliosphere?
- 3.2.1 How do energetic particles scatter and move along the interplanetary magnetic field?
- 3.2.1.1 Map the power spectrum of the turbulent magnetic field as a function of heliocentric distance in order to provide ground-truth for transport models
- 3.2.1.2 Measurements of SEP events time profiles and anisotropy in order to probe solar wind turbulence
- 3.2.1.3 Identify dropouts and measure scattering of SEPs by turbulence.
- 3.2.2 Latitudinal and longitudinal transport of SEPs
- 3.2.3 Properties and distribution of near-Sun shocks, their fluctuations and particle acceleration
- 3.2.4 How do large and small-scale structures modulate particle fluxes?
- 3.2.5 Shock-surfing acceleration mechanism
- 3.2.6 Effects of energetic particles propagating downward in the chromosphere
- 3.3 What are the seed populations for energetic particles?
- 3.1 How and where are energetic particles accelerated at the Sun?
- Objective 4: How does the solar dynamo work and drive connections between the Sun and the heliosphere?
- 4.0 Overall remarks and feasibility concerning Objective 4 observations with Solar Orbiter
- 4.1 How is magnetic flux transported to and re-processed at high solar latitudes?
- 4.1.1 Study the detailed solar surface flow patterns in the polar regions, including coronal hole boundaries.
- 4.1.2 Study the subtle cancellation effects that lead to the reversal of the dominant polarity at the poles
- 4.1.3 Explore the transport processes of magnetic flux from the activity belts towards the poles and the interaction of this flux with the already present polar magnetic field.
- 4.1.4 Study the influence of cancellations at all heights in the atmosphere
- 4.2 What are the properties of the magnetic field at high solar latitudes?
- 4.3 What is the nature of magnetoconvection?
- 4.4 Are there separate dynamo processes acting in the Sun?
- 4.5 How are coronal and heliospheric phenomena related to the solar dynamo?
- 5. Additional science objectives
- 5.1 Additional Science Objectives of EUI
- 5.2 Additional Science Objectives of EPD
- 5.3 Additional Science Objectives of MAG
- 5.4 Additional Science Objectives of METIS
- 5.4.1 Hydrogen Ly-α emission by the atmosphere of planets (e.g. Venus, Jupiter)
- 5.4.2 Study of Sungrazing comets
- 5.4.2.1 Understand cometary properties and evolution by mapping the hydrogen Ly-α emission, proportional to the outgassing rate, along its trajectory close to the Sun
- 5.4.2.2 Investigate the fragmentation of the cometary nucleus from the variation with the heliocentric distance of the outgassing rate and from the splitting of the cometary tail
- 5.5 Additional Science Objectives of PHI
- 5.6 Additional Science Objectives of RPW
- 5.7 Additional Science Objectives of SoloHI
- 5.8 Additional Science Objectives of SPICE
- 5.9 Additional Science Objectives of STIX
- 5.10 Additional Science Objectives of SWA
- 5.10.1 What is the temporal variability of 3D thermal particle distributions?
- 5.10.2 How are proton and helium temperatures related to their relative drift, is there any evidence for resonant heating?
- 5.10.3 How common are proton beams, where do they come from and what impact do they have on ambient conditions (wave generation, heating)?
- 5.10.4 Identify and characterise the various forms of free energy in the particle distribution functions
- 5.10.5 Fully characterise the radial and latitudinal variability of 3D thermal particle distributions under different solar wind conditions
- 5.10.6 Electron halo population
- 5.10.7 How do the combined electron strahl and composition signatures vary across reconnecting solar wind current sheets?
- Bibliography
- Sub-objectives not yet attached to SOOPs
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Andrew Walsh