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Inter- and Transdisciplinary Sessions
ST – Solar-Terrestrial Sciences
Programme group chairs:
Open Session on the Sun and Heliosphere (including Hannes Alfvén Medal Lecture by Daniel N. Baker)
This session traditionally provides a forum for the discussion of all aspects of solar and heliospheric physics. Popular topics have included solar cycle dependencies of the Sun, solar wind and heliosphere, Coronal Mass Ejection research, studies of energetic particles throughout the heliosphere, and the outer boundaries of the heliosphere. We encourage contributions related to all ongoing and planned space missions, to ground-based experiments and to theoretical research. Papers presenting ideas for future space missions and experiments are very welcome in this session. The session will consist of both oral and poster presentations.
Theory and Simulation of Solar System Plasmas: focus on the Sun and solar wind
The “Theory and Simulation of Solar System Plasmas” session solicits presentations of the latest results from theoretical investigations and numerical simulations in space plasma-physics from microscopic to global scales, in comparison with experiments and observations in the heliosphere: at the Sun, in the solar corona, in interplanetary space and in planetary magnetospheres. Each year a topic of special interest is chosen as a focus of the session. For 2019 this focus will be on the sun. Of particular interest is to understand plasma heating and particle acceleration processes as well as the resulting observable radiation processes. We encourage presentations of theory and modelling results directly relevant to current and forthcoming space missions, notably MMS, the Parker Solar Probe, Solar Orbiter and Bepi Colombo
Blowing in the Solar Wind: Understanding Solar Transients and their Heliospheric Impact
The solar wind is an uninterrupted flow of highly ionised plasma that fills interplanetary space and is crossed by strong transient perturbations such as coronal mass ejections (CMEs). These phenomena, in addition to corotating density structures and solar energetic particles (SEPs), drive a large range of disturbances to planetary atmospheres. Their properties and arrival times are, however, difficult to predict with reasonable accuracy. Observations from multiple vantage points, in-situ measurements from multiple positions and modelling efforts have been employed systematically to study the properties of the solar wind plasma and of CMEs, from their formation to their arrival at Earth and at planets throughout the inner heliosphere.
The recently launched Parker Solar Probe, the imminent launch of Solar Orbiter, as well as potential future missions at L1 and L5, and planetary missions that will measure the solar wind during their cruise phase (e.g. BepiColombo), will provide us with the perfect opportunity to test, validate, and refine the current knowledge of these physical phenomena and their interactions. Accordingly, the aim of this session is to showcase the latest observational and modelling efforts regarding the evolution of the solar wind and CMEs during their propagation throughout the heliosphere as seen from multiple vantage points, and to foresee future developments. Potential improvements to our current space weather forecasting capabilities will be highlighted.
Exploring the near-Sun environment and first observations of Parker Solar Probe
The Sun’s corona is the birthplace of the solar wind, coronal mass ejections and solar energetic particles which all are fundamental drivers of space weather. The key physical processes at the origin of these phenomena (i.e., heating and acceleration of the coronal plasma) have not been clarified to date. After the successful launch of NASA’s Parker Solar Probe (PSP) mission on August 12, 2018, the spacecraft will gradually reduce its distance to the Sun over the next years using seven Venus gravity assists and will reach a distance of less than 10 solar radii in 2024. Combining the PSP observations with data from the upcoming ESA Solar Orbiter mission, with remote sensing observations from SDO, STEREO and Proba2, with other in-situ data, e.g., from ACE and DSCOVR, with ground-based observations and with theoretical models will be a challenging and exciting task to help unravel unanswered science questions about the physics of the corona, solar wind and energetic particles. At times of the EGU General Assembly in early April 2019, PSP will have completed its first perihelion around the Sun end of 2018, with an unprecedented distance of 35 solar radii, and will just be beyond its 2nd perihelion. This session invites oral and poster contributions on all aspects of research addressed to the exploration of our near-Sun environment, including first observations from PSP and in preparation of the upcoming SO mission.
The majority of space plasmas are in a turbulent state, displaying fluctuations and nonlinear behaviour at a broad range of scales. A variety of these plasmas are also seen to be heated, with dissipation of turbulence as a possible explanation. Many aspects of the turbulence and heating, and their interaction with other space plasma phenomena (e.g., shocks, reconnection, and instabilities), however, remain to be fully understood. This session will address these questions through discussion of observational, theoretical, numerical, and laboratory work to understand these processes. This session is relevant to many currently operating and future missions (e.g., Wind, Cluster, MMS, STEREO, THEMIS, Van Allen Probes, DSCOVR, Parker Solar Probe and Solar Orbiter).
Dynamical processes and particle acceleration associated with current sheets, magnetic islands and turbulence-borne structures in different plasmas
Recent studies show that current sheets and magnetic islands observed in the solar wind play a significant role in local particle acceleration to keV-MeV energies, and the resulting energetic particle enhancements constitute a hazardous condition in the interplanetary and near-Earth space. Current sheets of various scales are self-organized structures that are ubiquitously formed in cosmic and laboratory plasmas owing to a change in the magnetic field direction, at strong discontinuities, and as a result of turbulence. Not surprisingly, dynamic processes occurring at current sheets and in their vicinity have a striking similarity in different plasmas. Current sheets experience magnetic reconnection that in turn leads to many subsequent nonlinear effects, triggering the development of a turbulent cascade, the formation of magnetic islands or flux ropes, and local acceleration of charged particles. These processes are observed from the corona to the outer heliosphere and may often be described by the same equations. They also can be linked physically as some of the structures originating from the corona survive and develop further in the solar wind. Meantime, these processes are usually studied by different scientific teams in independent ways.
This interdisciplinary session will bring together specialists from different plasma physics communities, bridging gaps in the understanding of the origin of coherent structures and the development of dynamical processes associated with current sheets. We invite researchers to share recent results of their theoretical studies, modelling and observations. Contributions that discuss and compare different mechanisms of local particle energization that occur in laboratory plasmas, the solar corona, magnetospheres of planets and the heliosphere are especially welcome. Furthermore, research results within the framework of the International Space Science Institute (ISSI) international team - 405 on 'Current Sheets, Turbulence, Structures and Particle Acceleration in the Heliosphere' (http://www.issibern.ch/teams/structpartaccel/index.html) will also be presented at this session.
The session should address all aspects of dust detection in space by both dedicated and non-dedicated dust detectors (i.e., electric field antennas, Faraday cups, etc.), theoretical approaches to detection mechanisms, and laboratory simulations of dust impact.
Solicited talk by Paul Kellogg (Minnesota Institute of Astrophysics, University of Minnesota, Minneapolis, MN, USA) focused on the dust impacts detected by STEREO.