Authors: P. Bochsler, F.M. Ipavich, J.A. Paquette, J.M. Weygand, and P. Wurz
Reference: J. Geophys. Res. 105 (A6), 12659-12666, 2000.
Abstract:
The Al/Mg abundance ratio provides an excellent test case for
investigating possible fractionation processes among low First
Ionization Potential (FIP) elements in the solar wind. Al and Mg are
refractory elements; their abundance ratio has been well determined in
solar system materials and inferences for the abundance ratio in the
solar atmosphere are reliable. Al and Mg are at neighboring masses and
have similar charge state properties in the solar corona; hence mass
fractionation effects in the solar wind acceleration process and
instrumental mass fractionation are minimal. From first observations
during two relatively short periods, one recorded in coronal hole
associated solar wind, the other in typical interstream solar wind, it
is concluded that the solar wind ratio in both regimes is consistent
with the solar system ratio. The Al/Mg ratio in interstream solar wind
is 0.081 ± 0012, and in the sample of coronal hole associated solar
wind it amounts to 0.076 ± 0.011. A comparison of these results with
the solar system ratio of 0.079 ± 0.005 gives no indication for
fractionation occurring among low FIP elements in the solar wind.