Abstract
In this review, the main models of ion-neutral frationation leading to an enhancement of the low FIP to high FIP abundance ratio in the corona or in the solar wind, are presented. Models based on diffusion parallel to the magnetic field are discussed; they are highly dependent on the boundary conditions. The magnetic field, that naturally separates ions from neutrals moving perpendicular to the field lines direction, when the ion-neutral frequency becomes lower than the ion gyrofrequency, is expected to play an active role in the ion-neutral separation. It is then suggested that ion-neutral fractionation is linked to the formation of the solar chromosphere, i.e. in magnetic flux-tubes at a temperature between 4000 and 6000 K.
Similar content being viewed by others
References
Athay, R.G.: 1981, Astrophys. J. 250, 709.
Ayres, T.R.: 1996, ‘Thermal bifurcation of the solar chromosphere', Stellar Surface Structure, IAU Symposium 173, Kluwer Academic Publishers, 371–384.
Burgers, J.M.: 1969, Flow Equations for Composite Gases, Academic Press, New York.
Feldman, U.: 1992, Physica Scripta 46, 202.
Fludra, A., Saba, J.L.R., Hénoux, J.-C., Murphy, R., Reames, D., Lemen, J.L., Strong, K.T., Sylwester, J., and Widing, K.: 1998, ‘Coronal Abundances', The Many Faces of the Sun, Strong, K.T., Saba, J.L.R., Haisch, B.M., and Schmelz, J.T. (eds.), Springer-Verlag, in press.
Fontenla, J.M., Avrett, E.H., and Loeser, R.: 1993, Astrophys. J. 406, 319.
Geiss, J. and Bochsler, P.: 1985, ‘Ion composition in the solar wind in relation to solar abundances', Rapports isotopiques dans le systeme solaire, Paris: Cepadues-Editions, 213–228.
Hénoux, J.-C.: 1995, ‘Models for explaining the observed spatial variation of element abundances — a review', Adv. Space Res. 15, (7)23-(7)32.
Hénoux, J.-C. and Somov, B.V.: 1991, ‘The photospheric dynamo: I. Magnetic flux-tube generation', Astron. Astrophys. 241, 613–617.
Hénoux, J.-C. and Somov, B.V.: 1992, ‘First ionization potential fractionation', Proceedings of the First SOHO Workshop, ESA SP-348, 325–330.
Hénoux, J.-C. and Somov, B.V.: 1997, ‘The photospheric dynamo: II. Physics of thin magnetic flux tubes', Astron. Astrophys. 318, 947–956.
Mandzhavidze, N. and Ramaty, R.: 1997, ‘Gamma Rays from Solar Flares', 23th IAU Genera Assembly, Kyoto.
Marsch, E., von Steiger, R. and Bochsler, P.: 1995, ‘Element fractionation by diffusion in the sola atmosphere', Astron. Astrophys. 301, 261–276.
Meyer, J.P.: 1993a, ‘Element Fractionation at Work in the Solar Atmosphere', Cosmic Abundance a Matter, N. Prantzos, E. Vangioni-Flam and M. Cassé (eds.), Cambridge Univ. Press, 26.
Meyer, J.P.: 1993b, Adv. Space Res. 13, (9)377.
Meyer, J.P.: 1996a, Cosmic Abundances, S.S. Holt and G. Sonneborn (eds.), ASP Conf. Series 99 127–146.
Meyer, J.P.: 1996b, The Sun and Beyond, J. Trân Thanh Vân, L. Celnikier, H.C. Trung and Vauclai (eds.), Gif-sur-Yvette: Editions Frontières, 27–46.
Peter, H.: 1996, ‘Velocity-dependent fractionation in the solar chromosphere', Astron. Astrophys 312, L37-L40.
Peter, H.: 1998a, ‘Element separation in the chromosphere', Space Sci. Rev., this volume.
Peter, H.: 1998b, private communication.
Reames, D.: 1998, ‘Solar Energetic Particles: Sampling Coronal Abundances', Space Sci. Rev., this volume.
Saba, J.L.R.: 1995, Adv. Space Res. 15, (7)13.
Schunk, R.W.: 1975, ‘Transport Equations for Aeronomy', Planet. Space Sci. 23, 437–485.
Share, G.H. and Murphy, R.J.: 1995, Astrophys. J. 464, 933–943.
von Steiger, R. and Geiss, J.: 1989, ‘Supply of fractionated gases to the corona', Astron. Astrophys 225, 222–238.
Vauclair, S.: 1996, ‘Element segregation in the solar chromosphere and the FIP bias: The Skimme model', Astron. Astrophys. 308, 228–232.
Wang, Y. M.: 1996, ‘Element separation by upward proton drag in the chromosphere', Astrophys. J 464, L91-L94.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hénoux, JC. FIP Fractionation: Theory. Space Science Reviews 85, 215–226 (1998). https://doi.org/10.1023/A:1005194215611
Issue Date:
DOI: https://doi.org/10.1023/A:1005194215611