Bonn 2010 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
EP: Fachverband Extraterrestrische Physik
EP 3: Poster
EP 3.17: Poster
Monday, March 15, 2010, 17:45–19:00, AKM Foyer
Heavy pickup ions at 1 AU — •Christian Drews1, Lars Berger1, Robert F. Wimmer-Schweingruber1, Antoinette B. Galvin2, Berndt Klecker3, and Eberhard Möbius2 — 1Institute for Experimental and Applied Physics, Christian-Albrechts-University zu Kiel, Germany — 2Space Science Center & Department of Physics, University of New Hampshire, New Hampshire — 3Max Planck Institute for Extraterrestrial Physics, Garching
Previous work has shown that pickup ions in the heliosphere are either of interstellar or solar wind origin. Because interstellar neutral He is focused by the gravitation of the Sun, count rates of interstellar He pickup ions show a distinctive peak when the observer has the Sun between himself and the interstellar inflow direction. Using the large geometric factor of the PLAsma and SupraThermal Ion Composition (PLASTIC) instrument on the Solar TErrestrial RElations Observators (STEREO) mission, we have clearly identified this so-called He focusing cone. Remarkably, not only He+ pickup ions are enhanced during these periods, but for the first time we also observe clear enhancements of Ne+ pickup ions during focusing cone passages.
The lower first ionization potentials (FIP) of Carbon and Oxygen in respect to Helium and Neon on the other hand, prevent these interstellar neutrals to penetrate deep into the heliosphere and a significant enhancement of C+ and O+ during cone passages is not observed. Indeed, the measured C/O ratio implies C+ and O+ to be primarily of solar wind origin.