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Title: VARIATIONS IN SOLAR WIND FRACTIONATION AS SEEN BY ACE/SWICS AND THE IMPLICATIONS FOR GENESIS MISSION RESULTS

We use Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer (SWICS) elemental composition data to compare the variations in solar wind (SW) fractionation as measured by SWICS during the last solar maximum (1999–2001), the solar minimum (2006–2009), and the period in which the Genesis spacecraft was collecting SW (late 2001—early 2004). We differentiate our analysis in terms of SW regimes (i.e., originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-first ionization potential (low-FIP) ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of SW speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.
Authors:
;  [1] ;  [2] ; ; ; ;  [3] ;  [4]
  1. Los Alamos National Laboratory, P.O. Box 1663, Los Alamos (NM) 87545 (United States)
  2. University of Montana, Department of Physics and Astronomy, 32 Campus Drive, Missoula, Montana (United States)
  3. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States)
  4. International Space Science Institute, Hallerstrasse 6, CH-3012 Bern (Switzerland)
Publication Date:
OSTI Identifier:
22518868
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 812; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CARBON; COMPARATIVE EVALUATIONS; CORRELATIONS; FRACTIONATION; HELIUM; IONIZATION POTENTIAL; MAGNESIUM; MASS; NEON; OXYGEN; PHOTOSPHERE; SOLAR CYCLE; SOLAR WIND; SPACE VEHICLES; SUN; VARIATIONS; VELOCITY