Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-26T17:49:44.288Z Has data issue: false hasContentIssue false

Radio remote sensing of the corona and the solar wind

Published online by Cambridge University Press:  01 September 2008

Steven R. Spangler
Affiliation:
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa, 52242, USA email: [email protected]
Catherine A. Whiting
Affiliation:
Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa, 52242, USA email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

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.

Modern radio telescopes are extremely sensitive to plasma on the line of sight from a radio source to the antenna. Plasmas in the corona and solar wind produce measurable changes in the radio wave amplitude and phase, and the phase difference between wave fields of opposite circular polarization. Such measurements can be made of radio waves from spacecraft transmitters and extragalactic radio sources, using radio telescopes and spacecraft tracking antennas. Data have been taken at frequencies from about 80 MHz to 8000 MHz. Lower frequencies probe plasma at greater heliocentric distances. Analysis of these data yields information on the plasma density, density fluctuations, and plasma flow speeds in the corona and solar wind, and on the magnetic field in the solar corona. This paper will concentrate on the information that can be obtained from measurements of Faraday rotation through the corona and inner solar wind. The magnitude of Faraday rotation is proportional to the line of sight integral of the plasma density and the line-of-sight component of the magnetic field. Faraday rotation provides an almost unique means of estimating the magnetic field in this part of space. This technique has contributed to measurement of the large scale coronal magnetic field, the properties of electromagnetic turbulence in the corona, possible detection of electrical currents in the corona, and probing of the internal structure of coronal mass ejections (CMEs). This paper concentrates on the search for small-scale coronal turbulence and remote sensing of the structure of CMEs. Future investigations with the Expanded Very Large Array (EVLA) or Murchison Widefield Array (MWA) could provide unique observational input on the astrophysics of CMEs.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2009

References

Bavassano, B., Dobrowolny, M., Mariani, F., & Ness, N. F. 1982, J. Geophys. Res., 87, 3616Google Scholar
Bird, M. K., Volland, H., Howard, R. A., Koomen, M. J., Michels, D. J., Sheeley, N. R., Armstrong, J. W., Seidel, B. L., Stelzried, C. T., & Woo, R. 1985, Solar Phys., 98, 341CrossRefGoogle Scholar
Bird, M. K. & Edenhofer, P. 1990, in Physics of the Inner Heliosphere II, Schwenn, R. and Marsch, E., ed., (Springer-Verlag:Berlin), p 13CrossRefGoogle Scholar
Efimov, A. I., Chashei, I. V., Shishov, V. I., & Bird, M. K. 1993, Astron. Lett., 19, 57Google Scholar
Gudiksen, B. V. & Nordlund, Å. 2005, ApJ, 618, 1020,; Erratum: ApJ, 623, 600Google Scholar
Hollweg, J. V., Bird, M. K., Volland, H., Edenhofer, P., Stelzried, C. T., & Seidel, B. L. 1982, J. Geophys. Res., 87, 1CrossRefGoogle Scholar
Ingleby, L. D., Spangler, S. R., & Whiting, C. A. 2007, ApJ, 668, 520Google Scholar
Kronberg, P. P., & Conway, R. G. 1970, MNRAS, 147, 149CrossRefGoogle Scholar
Liu, Y., Manchester, W. B. IV, Kasper, J. C., Richardson, J. D., & Belcher, J. W. 2007, ApJ, 665, 1439CrossRefGoogle Scholar
Mancuso, S. and Spangler, S. R. 2000, ApJ, 525, 195CrossRefGoogle Scholar
Mancuso, S. and Spangler, S. R. 2000, ApJ, 539, 480CrossRefGoogle Scholar
Mancuso, S. & Garzelli, M. V. 2006, A & A, 466, 5Google Scholar
Marsch, E. & Tu, C. Y. 1997, A & A, 319, L17Google Scholar
McKenzie, J. F., Banaszkiewicz, M., & Axford, W. I. 1995, A & A, 303, L45Google Scholar
Pätzold, M., Bird, M. K., Volland, H., Levy, G. S., Seidel, B. L., & Stelzried, C. T. 1987, Solar Phys., 109, 91CrossRefGoogle Scholar
Sakurai, T. and Spangler, S. R. 1994, ApJ, 434, 773CrossRefGoogle Scholar
Spangler, S. R., Leckband, J. A., & Cairns, I. H. 2000 Phys. Plasm., 4, 846CrossRefGoogle Scholar
Spangler, S. R. & Mancuso, S. 2000 ApJ, 530, 491Google Scholar
Spangler, S. R., Kavars, D. W., Kortenkamp, P. S., Bondi, M., Mantovani, F., & Alef, W. 2002, A & A, 384, 654CrossRefGoogle Scholar
Spangler, S. R. 2005, Space Sci. Revs, 121, 189CrossRefGoogle Scholar
Spangler, S. R. 2007, ApJ, 670, 841CrossRefGoogle Scholar