Abstract
Axially symmetric constant-alpha force-free magnetic fields in toroidal flux ropes with elliptical cross sections are constructed in order to investigate how their alphas and magnetic helicities depend on parameters of the flux ropes. Magnetic configurations are found numerically using a general solution of a constant-alpha force-free field with an axial symmetry in cylindrical coordinates for a wide range of oblatenesses and aspect ratios. Resulting alphas and magnetic helicities are approximated by polynomial expansions in parameters related to oblateness and aspect ratio. These approximations hold for toroidal as well as cylindrical flux ropes with an accuracy better than or of about 1%. Using these formulae, we calculate relative helicities per unit length of two (probably very oblate) magnetic clouds and show that they are very sensitive to the assumed magnetic cloud shapes (circular versus elliptical cross sections).
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References
Berger, M.A.: 1984, Rigorous new limits on magnetic helicity dissipation in the solar corona. Geophys. Astrophys. Fluid Dyn. 30, 79. DOI .
Berger, M.A.: 1999, Magnetic helicity in space physics. In: Brown, M.R., Canfield, R.C., Pevtsov, A.A. (eds.) Magnetic Helicity in Space and Laboratory Plasmas, Geophys. Monogr. Ser. 111, AGU, Washington, 1.
Berger, M.A., Field, G.B.: 1984, The topological properties of magnetic helicity. J. Fluid Mech. 147, 133. DOI .
Burlaga, L.F.: 1988, Magnetic clouds and force-free fields with constant alpha. J. Geophys. Res. 93, 7217. DOI .
Burlaga, L.F., Lepping, R.P., Jones, J.A.: 1990, Global configuration of a magnetic cloud. In: Russell, C.T., Priest, E.R., Lee, L.C. (eds.) Physics of Magnetic Flux Ropes, Geophys. Monogr. Ser. 58, AGU, Washington, 373. DOI .
Burlaga, L., Sittler, E., Mariani, F., Schwenn, R.: 1981, Magnetic loop behind an interplanetary shock: Voyager, Helios, and IMP 8 observations. J. Geophys. Res. 86, 6673. DOI .
Cap, F., Khalil, S.M.: 1989, Eigenvalues of relaxed axisymmetric toroidal plasmas of arbitrary aspect ratio and arbitrary cross-section. Nucl. Fusion 29, 1166.
Cargill, P.J., Chen, J., Spicer, D.S., Zalesak, S.T.: 1995, Geometry of interplanetary magnetic clouds. Geophys. Res. Lett. 22, 647. DOI .
Dasso, S., Mandrini, C.H., Démoulin, P., Farrugia, C.J.: 2003, Magnetic helicity analysis of an interplanetary twisted flux tube. J. Geophys. Res. 108, 1362 DOI .
Goldstein, H.: 1983, On the field configuration in magnetic clouds. In: Neugebauer, M. (ed.) Solar Wind Five, NASA Conf. Publ. CP-2280, NASA, Washington, 731.
Hidalgo, M.A., Nieves-Chinchilla, T.: 2012, A global magnetic topology model for magnetic clouds. I. Astrophys. J. 748, 109. DOI .
Hidalgo, M.A., Cid, C., Viñas, A.F., Sequeiros, J.: 2002, A non-force-free approach to the topology of magnetic clouds in the solar wind. J. Geophys. Res. 107, 1002 DOI .
Hu, Q., Qiu, J., Krucker, S.: 2015, Magnetic field line lengths inside interplanetary magnetic flux ropes. J. Geophys. Res. 120, 5266. DOI .
Hu, Q., Sonnerup, B.U.Ö.: 2002, Reconstruction of magnetic clouds in the solar wind: orientations and configurations. J. Geophys. Res. 107, 1142 DOI .
Hu, Q., Qiu, J., Dasgupta, B., Khare, A., Webb, G.M.: 2014, Structures of interplanetary magnetic flux ropes and comparison with their solar sources. Astrophys. J. 793, 53. DOI .
Janvier, M., Démoulin, P., Dasso, S.: 2013, Global axis shape of magnetic clouds deduced from the distribution of their local axis orientation. Astron. Astrophys. 556, A50. DOI .
Janvier, M., Démoulin, P., Dasso, S.: 2014a, Are there different populations of flux ropes in the solar wind? Solar Phys. 289, 2633. DOI .
Janvier, M., Démoulin, P., Dasso, S.: 2014b, In situ properties of small and large flux ropes in the solar wind. J. Geophys. Res. 119, 7088. DOI .
Klein, L.W., Burlaga, L.F.: 1982, Interplanetary magnetic clouds at 1 AU. J. Geophys. Res. 87, 613. DOI .
Krimigis, S., Sarris, E., Armstrong, T.: 1976, Evidence for closed magnetic loop structures in the interplanetary medium (abstract). Eos Trans. AGU 57, 304.
Leamon, R.J., Canfield, R.C., Jones, S.L., Lambkin, K., Lundberg, B.J., Pevtsov, A.A.: 2004, Helicity of magnetic clouds and their associated active regions. J. Geophys. Res. 109, A05106. DOI .
Lepping, R.P., Jones, J.A., Burlaga, L.F.: 1990, Magnetic field structure of interplanetary magnetic clouds at 1 AU. J. Geophys. Res. 95, 11957. DOI .
Lepping, R.P., Wu, C.-C., Berdichevsky, D.B.: 2015, Yearly comparison of magnetic cloud parameters, sunspot number, and interplanetary quantities for the first 18 years of the Wind mission. Solar Phys. 290, 553. DOI .
Lepping, R.P., Berdichevsky, D.B., Szabo, A., Arqueros, C., Lazarus, A.J.: 2003, Profile of an average magnetic cloud at 1 AU for the quiet solar phase: Wind observations. Solar Phys. 212, 425. DOI .
Lepping, R.P., Berdichevsky, D.B., Wu, C.-C., Szabo, A., Narock, T., Mariani, F., Lazarus, A.J., Quivers, A.J.: 2006, A summary of Wind magnetic clouds for years 1995 – 2003: model-fitted parameters, associated errors and classifications. Ann. Geophys. 24, 215. DOI .
Lundquist, S.: 1950, Magnetohydrostatic fields. Ark. Fys. 2, 361.
Marubashi, K.: 1986, Structure of the interplanetary magnetic clouds and their solar origins. Adv. Space Res. 6, (6)335. DOI .
Marubashi, K.: 1997, Interplanetary magnetic flux ropes and solar filaments. In: Crooker, N., Joselyn, J., Feyman, J. (eds.) Coronal Mass Ejections, Geophys. Monogr. Ser. 99, AGU, Washington, 147.
Moldwin, M.B., Hughes, W.J.: 1991, Plasmoids as magnetic flux ropes. J. Geophys. Res. 96, 14051. DOI .
Mulligan, T., Russell, C.T.: 2001, Multispacecraft modeling of the flux rope structure of interplanetary coronal mass ejections: cylindrically symmetric versus nonsymmetric topologies. J. Geophys. Res. 106, 10581. DOI .
Pevtsov, A.A., Canfield, R.C.: 2001, Solar magnetic fields and geomagnetic events. J. Geophys. Res. 106, 25191. DOI .
Press, V.H., Teukolsky, S.A., Vetterling, W.T., Flannery, B.P.: 2002, Numerical Recipes in C, The Art of Scientific Computing, Second Edition, Cambridge University Press, New York.
Riley, P., Crooker, N.U.: 2004, Kinematic treatment of coronal mass ejection evolution in the solar wind. Astrophys. J. 600, 1035. DOI .
Riley, P., Linker, J.A., Lionello, R., Mikic, Z., Odstrcil, D., Hidalgo, M.A., Cid, C., Hu, Q., Lepping, R.P., Rees, A.: 2004, Fitting flux ropes to a global MHD solution: a comparison of techniques. J. Atmos. Solar-Terr. Phys. 66, 1321. DOI .
Romashets, E., Vandas, M., Poedts, S.: 2010, Modeling of local magnetic field enhancements within solar flux ropes. Solar Phys. 261, 271. DOI .
Russell, C.T., Mulligan, T.: 2002, The true dimensions of interplanetary coronal mass ejections. Adv. Space Res. 29, 3, 301. DOI .
Shimazu, H., Marubashi, K.: 2000, New method for detecting interplanetary flux ropes. J. Geophys. Res. 105, 2365. DOI .
Song, H.Q., Chen, Y., Zhang, J., Cheng, X., Wang, B., Hu, Q., Li, G., Wang, Y.M.: 2015, Evidence of the solar EUV hot channel as a magnetic flux rope from remote-sensing and in situ observations. Astrophys. J. Lett. 808, L15. DOI .
Tsuji, Y.: 1991, Force-free magnetic field in the axisymmetric torus of arbitrary aspect ratio. Phys. Fluids, B 3, 3379. DOI .
Vandas, M., Romashets, E.P.: 2003, A force-free field with constant alpha in an oblate cylinder: A generalization of the Lundquist solution. Astron. Astrophys. 398, 801. DOI .
Vandas, M., Romashets, E.: 2015, Comparative study of a constant-alpha force-free field and its approximations in an ideal toroid. Astron. Astrophys. 580, A123. DOI .
Vandas, M., Romashets, E.P., Geranios, A.: 2010, How do fits of simulated magnetic clouds correspond to their real shapes in 3-D? Ann. Geophys. 28, 1581. DOI .
Vandas, M., Romashets, E., Geranios, A.: 2015, Modeling of magnetic cloud expansion. Astron. Astrophys. 583, A78. DOI .
Vandas, M., Romashets, E.P., Watari, S.: 2005, Magnetic clouds of oblate shapes. Planet. Space Sci. 53, 19. DOI .
Vandas, M., Fischer, S., Dryer, M., Smith, Z., Detman, T.: 1995, Simulation of magnetic cloud propagation in the inner heliosphere in two-dimensions, 1, A loop perpendicular to the ecliptic plane. J. Geophys. Res. 100, 12285. DOI .
Acknowledgements
We acknowledge the use of data from OMNIWeb and the PIs who provided them. This work was supported by projects 14-19376S and 17-06065S from GA ČR and by the AV ČR grant RVO:67985815.
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Vandas, M., Romashets, E. Toroidal Flux Ropes with Elliptical Cross Sections and Their Magnetic Helicity. Sol Phys 292, 129 (2017). https://doi.org/10.1007/s11207-017-1149-5
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DOI: https://doi.org/10.1007/s11207-017-1149-5