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Magnetic Helicity in Sigmoids, Coronal Mass Ejections and Magnetic Clouds

Published online by Cambridge University Press:  30 March 2016

D. M. Rust
D. M. Rust*
Affiliation:
The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA

Abstract

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Sigmoids, coronal mass ejections (CMEs) and magnetic clouds (MCs) all show signatures of twisted and writhing magnetic fields. CMEs are often associated with MCs, whose fields are regularly mapped with sensitive magnetometers. These measurements reveal that MC fields are helical, and each MC carries magnetic helicity away from the sun. It is more difficult to determine the magnetic helicity of the corresponding features on the sun. This presentation surveys recent work on helicity in solar features, focusing especially on the interpretation of sigmoids, which are S-shaped, bright features seen in images from the Yohkoh soft X-ray telescope. Several lines of evidence indicate that sigmoids are twisted and writhing flux ropes that erupt as components of CMEs. CMEs may be initiated by MHD-instable flux ropes. The fact that the ejected flux ropes carry off a large amount of positive helicity from the south and negative helicity from the north each solar cycle implies an equal, compensating flow of helicity through the sun’s equatorial plane.

Type
I. Joint Discussions
Information
Highlights of Astronomy , Volume 13 , 2005 , pp. 105 - 108
Copyright
Copyright © Astronomical Society of Pacific 2005

References

Baty, H., Einaudi, G., Lionello, R., & Velli, M. 1998, A&A, 333, 313 Google Scholar
Berger, M. 1999, in Magnetic Helicity in Space and Laboratory Plasmas, eds. Brown, M. Canfield, R., & Pevtsov, A., AGU Geophys. Monog. 111, 1 Google Scholar
Berger, M. A., & Ruzmaikin, A. 2000, JGR, 105, 10481 Google Scholar
Bieber, J. W., & Rust, D. M. 1995, ApJ, 453, 911 CrossRefGoogle Scholar
Blackman, E. G., & Brandenburg, A. 2003, ApJ, 584, L99 Google Scholar
Bleybel, A., Amari, T., van Driel, L., & Leka, K. D. 2002, A&A, 395, 685 Google Scholar
Brandenburg, A., Bigazzi, A., & Subramanian, K. 2001, MNRAS, 325, 685 CrossRefGoogle Scholar
Brandenburg, A., & Dobler, W. 2001, A&A, 369, 329 Google Scholar
Burlaga, L. F., et al. 1982, GRL, 9, 1317 CrossRefGoogle Scholar
Canfield, R. C., Hudson, H. S., & McKenzie, D. E. 1999, GRL, 26, 627 Google Scholar
Chae, J. 2001, ApJ, 560, L95 Google Scholar
Démoulin, P., et al. 2002, A&A, 382, 650 Google Scholar
DeVore, C. R. 2000, ApJ, 539, 944 Google Scholar
Kusano, K., Maeshiro, T., Yokoyama, T., & Sakurai, T. 2002, ApJ, 577, 501 Google Scholar
Longcope, D. W., Fisher, G. H., & Pevtsov, A. A. 1998, ApJ, 507, 417 Google Scholar
Low, B. C., & Berger, M. A. 2003, ApJ, 589, 644 CrossRefGoogle Scholar
Moore, R., Sterling, A., Hudson, H., & Lemen, J. 2001, ApJ, 552, 833 CrossRefGoogle Scholar
Pevtsov, A. A., Canfield, R. C., & McClymont, A. N. 1997, ApJ, 481, 973 Google Scholar
Pevtsov, A. A., Maleev, V. M., & Longcope, D. W. 2003, ApJ, 593, 1217 CrossRefGoogle Scholar
Rust, D. M. 1994, GRL, 21, 241 CrossRefGoogle Scholar
Rust, D. M., & Kumar, A. 1996, ApJ, 464, L199 Google Scholar
Ruzmaikin, A., Martin, S., & Hu, Q. 2003, JGR, 108b Google Scholar
Sakurai, T. 1976, PASJ, 28, 177 Google Scholar
Titov, V. S., Priest, E. R., & Démoulin, P. 1993, A&A, 276, 564 Google Scholar