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www.ieap.uni-kiel.de/et/ag-wimmer/ | 18. 12. 2018

AG Wimmer-Schweingruber

Fahne Deutschland


Contents of Research

Measuring the composition of the solar wind is important for three reasons:

  1. When the solar system was formed about 4.6 billion years ago, the sun was formed out of the same pre-solar cloud that formed the planets, moon, comets and asteroids. Researchers in planetology use the composition of the sun as a reference for the variations in the forming of other celestial bodies. The solar wind offers the best possible samples of solar material.
  2. Changes in the composition of the solar wind are determined in the chromosphere and the corona. They stay frozen in interplanetary medium and can therefore be used as tracers for the origin of interplanetary plasma
  3. Differences between the composition of the solar wind and optically determined element frequencies in the photosphere and (sometimes) meteors can be used to examine the complicated physical plasma processes in the solar atmosphere.

Suprathermal Particles

Measuring suprathermal particles (particles that are in the energy range above the thermal distribution of the solar wind) is important because these particles serve as sources for the further acceleration of to even higher energies. Knowledge of the composition of these particles makes it possible to study the acceleration processes. Determining the speed and energy distribution functions allows us to draw conclusions about the wave-particle interaction that plays an important roll in the acceleration processes. Here the changes in the energy dependent composition (as ratio of abundance) are especially relevant because it can minimize the influence of instrumental uncertainty.

High Energy Particles

High energy particles, in spite of their high energy, are influenced by many processes in the heliosphere. The heliosphere on a large scale, heavily influenced by the sun, affects the intensity of the galactic cosmic radiation on the earth and other planets. On a smaller scale, the long living so-called corotating interaction regions (CIRs) and coronal mass ejections (CMEs) affect the flow of high energy particles.

Cosmic Radiation

The intensity of galactic cosmic radiation (GCR) is approximately inverse to the average number of sunspots, which is a measurement for the activity of the sun. This modulation of the galactic cosmic radiation is often caused by simple phenomena, especially by the diffusion of GCR through the heliosphere with a diffusion tensor depending on the region. Other models include drift mechanisms that could affect the intensity of different particle types.