The Abundance of Sodium in the Solar Wind as Measured by SOHO/CELIAS/MTOF

Authors: Fred M Ipavich, Peter Bochsler, Scott E Lasley, John A Paquette, and Peter Wurz
Reference: AGU Abstract, Spring 1999

Abstract: The first determination of the Na abundance in the solar wind is reported. Na with its 5.12 V First Ionization Potential (FIP) is the most extreme low-FIP element observed in the solar wind to date. The proximity of Na to Ne in mass as well as the similar and narrow charge state distributions of Na and Ne in the corona render these two elements as almost ideal markers to accurately identify small variations between low- and high-FIP solar wind with CELIAS/MTOF. The short first ionization time of Na and the relation of the solar wind Na abundance to a very well known photospheric value make it a prime candidate for investigating coronal-hole associated FIP fractionation and for sensitive testing of FIP/FIT models. The behavior of Na relative to low-FIP and high-FIP elements is compared, for both interstream and coronal-hole associated solar wind flows. Preliminary results indicate that Na behaves as expected for a low-FIP element in these two types of solar wind flows.

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Last Update: March 10, 2000, James Weygand