WG1: Solar
WG2: Interplanetary
Origin and Evolution of the Solar Wind (Ilia Roussev, Bill Abbett)
- What fraction of the network magnetic field closes below the corona in the network and in the internetwork?
- How does the network (and internetwork) magnetic field map into the corona for a variety of different distributions of magnetic field elements throughout the network and the internetwork?
- How much magnetic energy dissipation is expected as a consequence of the supergranular transport of internetwork fields into the network and of the consequent reconnection?
- What fraction of this dissipated magnetic energy gets to the corona, in what form does it get there, and by what path?
- Is most of the lower corona emission produced on recently reconnected field lines (and thus transiently heated field lines) connecting the network to the internetwork?
Magnetic (and Other) Data Input into Global Models (Ilia Roussev, Bill Abbett)
This session will discuss how to make a best use of solar magnetograms in global computational models of the solar corona and solar wind. The aim of this session is to learn more about the advantages and limitations of the available magnetic data and numerical models. Observers will discuss the standard and alternative approaches as well as reduction techniques of those data. Numerical modelers will discuss what boundary conditions and observed data inputs are used in MHD calculations of the steady-state solar corona and solar wind as well as transient phenomena.
WG3: Energetic Particles
Origin and Evolution of Suprathermal Ion Populations in the Solar Corona and the Interplanetary Medium (Mihir Desai, John Raymond)
This is a follow-up to the introductory session on sources of suprathermal ions from last year‘s workshop. This session will bring together experts from the heliospheric solar wind and the energetic particle communities with those from the solar coronal spectroscopic community along with theoreticians in attempt to understand the origin and evolution of the suprathermal tail. In this session, we hope to identify and characterize key properties of various ion sources and quantify their relative contributions to the suprathermal tail over the course of a solar cycle
Where can CME shocks form in the solar corona? (Simon Plunkett, Mihir Desai)
This session will address the following two questions: “what do the time differences between X-ray, radio, CME and SEP observations tell us about where shocks are first formed in the solar corona, and how do they relate to the SEPs observed at 1 AU?
Turbulence (Randy Jokipii, Joe Giacalone)
This session will focus on current understanding of the effects of photospheric flows (supergranulation, etc) on determining the magnetic field at the Sun, the effects of the solar wind in advecting this field out from the Sun, and the resulting dynamics and structure of the turbulent magnetic field in the solar wind.
Shock geometry and particle injection at shocks (Gang Li, Christina Cohen)
While most large SEP events have shocks associated with them, not all CME-driven shocks can produce large SEP events and even the typically smaller ESP events near Earth. Conceivably, the injection mechanism plays an important role. A strongly related topic to the injection problem is that of electron acceleration at shocks. It has been argued that electrons probably owing to having smaller gyro-radii may not be efficiently accelerated at shocks as ions.This session will address the ion injection problem and the acceleration of electrons by shocks.
Particle spectrum and upstream (downstream) phenomena (Gang Li, Ilia Roussev)
Spectra observed in many large SEP events (CME-shock related) show various shapes: some have sharp breaks and behave like double power laws while others have exponential roll-overs. The shape of different heavy ions often can be organized by (Q/A)δ where δ differs from one event to another, and Q/A is the ion’s charge-to-mass ratio. The Q/A-dependence of the spectra probably reflects the properties of upstream and downstream plasma, such as the form and intensity of upstream wave power and possibly the shock geometry. This session will start with detailed observations of these events and then discuss the pros and cons of various theoretical explanations that have been put forward to account for these unique data.
The Historic Solar Event of January 20, 2005: A Challenge for Current Theories on the Origins of Solar Energetic Particles? (Allan Tylka, Mihir Desai)
The solar particle event of January 20, 2005 was the largest since 1956. The event was also characterized by fast rise times and hard energy spectra, both at the Sun and in interplanetary space. The exceptional nature of this event may challenge the most-widely accepted paradigm for the origin of large solar particle events, in which the primary acceleration is ascribed to shocks driven by fast coronal mass ejections. Our particular focus will be the implications of this event for our current theories on the origin of solar energetic particles. Among the questions we hope to address are:
- What features of the interplanetary energetic particles – if any – cannot be explained in terms of shock acceleration?
- What is the relationship – if any – between the particles observed in interplanetary space and those observed at the Sun by RHESSI through their interactions in the solar atmosphere?
- What characteristics of the corona and/or interplanetary space caused this event to be so exceptional?
- What is the current status of efforts to simulate this particle event?
CIRs and Energetic Particles (Mihir Desai, Ilia Roussev, I. Richardson)
By testing current theories with key observations from Ulysses, Wind, ACE, and SoHO, this session will provide a forum and context for the exciting new studies we hope to undertake during the upcoming solar minimum.
- What causes the systematic differences between the solar wind and CIR composition? In particular, that the C/O ratio in CIR-accelerated particles is significantly higher has been known for more than thirty years, but we still have no satisfactory explanation?
- What are the mechanisms that accelerate ions from the solar wind suprathermal tail and pick up ion populations? Is there a role for non-shock related processes such as stochastic acceleration, acceleration by solar wind velocity gradients, and compression regions?
- Where and how are the particles observed at 1 AU and at higher latitudes accelerated (for instance, the lowest energy particles observed could not propagate from a CIR at several AU and lower latitudes)? Is there any local acceleration?
- What properties of CIRs/high speed streams modulate the galactic cosmic ray intensity, and why does the amplitude of such modulations appear to be larger in alternate solar minima?
- How are low energy ion enhancements and cosmic ray modulations manifested at high latitudes well beyond the extent of CIR? What are the contributions of non-Parker spiral field lines, transverse diffusion, local solar wind structures, for example?
- Can the propagation of Jovian electrons and their modulation by CIRs, provide insight into CIR particle transport?