Hostname: page-component-848d4c4894-p2v8j Total loading time: 0 Render date: 2024-04-30T10:40:08.191Z Has data issue: false hasContentIssue false
  • English
  • Français

Fractionation of the Solar Wind

Published online by Cambridge University Press:  30 March 2016

R. Von Steiger
R. Von Steiger*
Affiliation:
Physikalisches Institut, Sidlerstrasse 5, CH-3012 Bern, Switzerland

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The composition of the solar wind (SW) is not a true sample of the solar composition, but it is fractionated with respect to the solar photosphere. This fractionation follows the well-known first ionization potential (FIP) pattern: When plotting the SW abundances with respect to the solar abundances as a function of FIP, a step function is obtained (Fig. 1). The step at ∼ 10eV has a height of 3-5 in the slow SW, but this is reduced to 1.5-2 in the fast streams, which originate in the coronal holes. The data given in Fig. 1 are collected and discussed in von Steiger & Geiss (1994), including the “FIP exceptions”, Kr and Xe.

The process leading to the observed overabundance of the low-FIPs has been located to operate by atom-ion separation across magnetic field lines in the chromosphere (Geiss, 1982), because this is the only region of the solar atmosphere where a significant fraction of the gas is neutral. The fractionated abundances observed in the S W are thus important tracers for processes and conditions at this site.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 10: Highlights of Astronomy. As presented at the XXIInd General Assembly of the IAU, 1994 , 1995 , pp. 310 - 312
Copyright
Copyright © Kluwer 1995

References

Antiochos, S.K. (1990) Eos Trans. AGU 71(17), 587 Google Scholar
Geiss, J. (1982) Space Sci. Rev. 33, 201 CrossRefGoogle Scholar
Geiss, J., & Bochsler, P. (1985) in: Rapports Isotopiques dans le Système Solaire, Toulouse: Cepadues-Editions, pp. 213–228 Google Scholar
Hénoux, J.-C., & Somov, B.V. (1992) ESA SP-348, 325–330 Google Scholar
Marsch, E., von Steiger, R., & Bochsler, P. (1994) submitted to A&A Google Scholar
Meyer, J.-P. (1993) in: Prantzos, N. et al. (eds), Origin and Evolution of the Elements, Cambridge Univ. Press, pp. 26–62 Google Scholar
Tagger, M., Shukorov, A.M., & Falgarme, E. (1994) A&A, in preparationGoogle Scholar
Vauclair, S. (1994) submitted to A&A Google Scholar
Vauclair, S., & Meyer, J.-P. (1985) in: Proc. 19th Internat. Cosmic Ray Conf., p. 230 Google Scholar
von Steiger, R., & Geiss, J. (1989) A&A 225, 222–238 Google Scholar
von Steiger, R., & Geiss, J. (1994) in: Jokipii, J.R. et al. (eds), Cosmic Winds and the Heliosphere, Tucson: University of Arizona Press, submittedGoogle Scholar