Aachen PK 2003 – wissenschaftliches Programm

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PV: Plenarvorträge

PV I

PV I: Plenarvortrag

Montag, 17. März 2003, 14:00–14:45, FO1

Introduction to solar wind — •Viviane Pierrard — IASB-BIRA, 3 av. Circulaire, B-1180 Brussels, Belgium

The solar wind is a space plasma constituted mainly by electrons and protons escaping continuously from the solar corona to the interplanetary space. It blows from the surface of the Sun at an average velocity ranging from 350 km/s to over 800 km/s in the high-speed solar wind escaping from the coronal holes. These particles interact with the magnetosphere of the Earth and create phenomena like aurora and magnetic storms.

The main characteristics of the solar wind particles will be described, with special attention for the more recent discoveries. These characteristics are better and better known from spacecraft and ultraviolet coronal spectroscopic observations. Traces of heavy ions have been identified in the solar wind. Among these particles, helium ions are the most abundant but oxygen, carbon and iron ions are also detected. These multi-ionized particles give important information on the solar wind acceleration process due to their large range of mass and charge states. More and more detailed observations have put strong constraints on the mechanisms proposed to heat the corona and accelerate the solar wind up to very high velocities. These mechanisms constitute major unsolved problems in solar physics. Among other proposed processes, the velocity filtration effect is a promising candidate.