@article{HassaninKliemSeehafer2016,
  author    = {Hassanin, Alshaimaa and Kliem, Bernhard and Seehafer, Norbert},
  title     = {Helical kink instability in the confined solar eruption on 2002 May 27},
  series = {Astronomische Nachrichten = Astronomical notes},
  volume    = {337},
  journal   = {Astronomische Nachrichten = Astronomical notes},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0004-6337},
  doi       = {10.1002/asna.201612446},
  pages     = {1082 -- 1089},
  year      = {2016},
  language  = {en}
}
@article{SeehaferFuhrmannValorietal.2007,
  author    = {Seehafer, Norbert and Fuhrmann, M. and Valori, Gherardo and Kliem, Bernhard},
  title     = {Force-free magnetic fields in the solar atmosphere},
  year      = {2007},
  language  = {en}
}
@article{KliemSeehafer2022,
  author    = {Kliem, Bernhard and Seehafer, Norbert},
  title     = {Helicity shedding by flux rope ejection},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {659},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/202142422},
  pages     = {9},
  year      = {2022},
  abstract  = {We quantitatively address the conjecture that magnetic helicity must be shed from the Sun by eruptions launching coronal mass ejections in order to limit its accumulation in each hemisphere. By varying the ratio of guide and strapping field and the flux rope twist in a parametric simulation study of flux rope ejection from approximately marginally stable force-free equilibria, different ratios of self- and mutual helicity are set and the onset of the torus or helical kink instability is obtained. The helicity shed is found to vary over a broad range from a minor to a major part of the initial helicity, with self helicity being largely or completely shed and mutual helicity, which makes up the larger part of the initial helicity, being shed only partly. Torus-unstable configurations with subcritical twist and without a guide field shed up to about two-thirds of the initial helicity, while a highly twisted, kink-unstable configuration sheds only about one-quarter. The parametric study also yields stable force-free flux rope equilibria up to a total flux-normalized helicity of 0.25, with a ratio of self- to total helicity of 0.32 and a ratio of flux rope to external poloidal flux of 0.94. These results numerically demonstrate the conjecture of helicity shedding by coronal mass ejections and provide a first account of its parametric dependence. Both self- and mutual helicity are shed significantly; this reduces the total initial helicity by a fraction of ∼0.4--0.65 for typical source region parameters.},
  language  = {en}
}
@article{SchumacherKliemSeehafer2000,
  author    = {Schumacher, J{\"o}rg and Kliem, Bernhard and Seehafer, Norbert},
  title     = {Three-dimensional spontaneous magnetic reconnection in neutral current sheets},
  year      = {2000},
  language  = {en}
}
@book{SchumacherKliemSeehafer1999,
  author    = {Schumacher, J{\"o}rg and Kliem, Bernhard and Seehafer, Norbert},
  title     = {Three-dimensional spontaneous magnetic reconnection in neutral current sheets},
  series = {Preprint series / Astrophysikalisches Institut Potsdam},
  volume    = {99,42},
  journal   = {Preprint series / Astrophysikalisches Institut Potsdam},
  publisher = {AIP},
  address   = {Potsdam},
  pages     = {26 S. : graph. Darst.},
  year      = {1999},
  language  = {en}
}
@article{KliemRustSeehafer2010,
  author    = {Kliem, Bernhard and Rust, S. and Seehafer, Norbert},
  title     = {Helicity transport in a simulated coronal mass ejection},
  series = {Proceedings of the International Astronomical Union},
  journal   = {Proceedings of the International Astronomical Union},
  publisher = {International Astronomical Union},
  address   = {Cambridge},
  issn      = {1743-9213},
  doi       = {10.1017/S1743921311006715},
  pages     = {125 -- 128},
  year      = {2010},
  language  = {en}
}
@misc{KliemRustSeehafer2010,
  author    = {Kliem, Bernhard and Rust, S. and Seehafer, Norbert},
  title     = {Helicity transport in a simulated coronal mass ejection},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {569},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-41290},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-412907},
  pages     = {125 -- 128},
  year      = {2010},
  abstract  = {It has been suggested that coronal mass ejections (CMEs) remove the magnetic he-licity of their coronal source region from the Sun. Such removal is often regarded to be necessary due to the hemispheric sign preference of the helicity, which inhibits a simple annihilation by reconnection between volumes of opposite chirality. Here we monitor the relative magnetic he-licity contained in the coronal volume of a simulated flux rope CME, as well as the upward flux of relative helicity through horizontal planes in the simulation box. The unstable and erupting flux rope carries away only a minor part of the initial relative helicity; the major part remains in the volume. This is a consequence of the requirement that the current through an expanding loop must decrease if the magnetic energy of the configuration is to decrease as the loop rises, to provide the kinetic energy of the CME.},
  language  = {en}
}
@article{HassaninKliemSeehaferetal.2022,
  author    = {Hassanin, Alshaimaa and Kliem, Bernhard and Seehafer, Norbert and T{\"o}r{\"o}k, Tibor},
  title     = {A model of homologous confined and ejective eruptions involving kink instability and flux cancellation},
  series = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  volume    = {929},
  journal   = {The astrophysical journal : an international review of spectroscopy and astronomical physics},
  number    = {2},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {2041-8205},
  doi       = {10.3847/2041-8213/ac64a9},
  pages     = {7},
  year      = {2022},
  abstract  = {In this study, we model a sequence of a confined and a full eruption, employing the relaxed end state of the confined eruption of a kink-unstable flux rope as the initial condition for the ejective one. The full eruption, a model of a coronal mass ejection, develops as a result of converging motions imposed at the photospheric boundary, which drive flux cancellation. In this process, parts of the positive and negative external flux converge toward the polarity inversion line, reconnect, and cancel each other. Flux of the same amount as the canceled flux transfers to a flux rope, increasing the free magnetic energy of the coronal field. With sustained flux cancellation and the associated progressive weakening of the magnetic tension of the overlying flux, we find that a flux reduction of approximate to 11\% initiates the torus instability of the flux rope, which leads to a full eruption. These results demonstrate that a homologous full eruption, following a confined one, can be driven by flux cancellation.},
  language  = {en}
}