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