A1 Refereed original research article in a scientific journal
Coronal Mass Ejection and Heliospheric Current Sheet Interaction Causing a Long-duration Magnetic Field Sector Transition; 
Authors: Temmer, Manuela; Heinemann, Stephan G.; Dresing, Nina; Dumbovic, Mateja; Asvestari, Eleanna
Publisher: Institute of Physics Publishing
Publication year: 2026
Journal: Astrophysical Journal
Article number: 203
Volume: 1004
Issue: 2
ISSN: 0004-637X
eISSN: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ae6dab
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Open Access publication channel
Web address : https://doi.org/10.3847/1538-4357/ae6dab
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/533831944
Self-archived copy's licence: CC BY
Self-archived copy's version: Publisher`s PDF
We present a study that combines remote-sensing and in situ observations of coronal mass ejections (CMEs) interacting with the nearby heliospheric current sheet (HCS). The sequence of eruptive events under study culminates in the largest directly observed flare of solar cycle 25 on 2024 October 3, producing a fast halo CME. Their source region can be linked to a so-called nested active region (or active longitude) that persisted over several solar rotations. Such long-lived regions reflect deep-seated magnetic structures that shape the global magnetic field configuration. By applying the drag-based CME propagation model, we connect the near-Sun observations from several CMEs during that activity period with in situ measurements. While one of the CMEs propagated on the opposite side of the HCS from Earth, and therefore did not produce in situ signatures near Earth, we detect, over the period 2024 October 5–10, a complex of HCS and CME structures propagating together with a shock ahead of them. The HCS seems to be locally replaced by the CME signatures, leading to a long-duration sector reversal of more than 48 hr. This event highlights the intrinsic connection between solar surface structures, the global magnetic field, and the evolution of complex eruptive events.
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We thank the anonymous referee for the valuable comments, which helped improve the study. M.T. and M.D. acknowledge support from the Austrian-Croatian Bilateral Scientific Project “Analysis of solar eruptive phenomena from cradle to grave.” S.G.H. acknowledges funding from the Austrian Science Fund (FWF) Erwin-Schrödinger fellowship [10.55776/J4560] and funding from the Research Council of Finland (Academy Fellowship) [370747; RIB-Wind]. N.D. is grateful for support by the Research Council of Finland (SHOCKSEE, grant No. 346902, and AIPAD, grant No. 368509). E.A. acknowledges support from the Research Council of Finland (Research Fellow grant No. 355659). M.D. acknowledges support from the European Union—NextGenerationEU within the framework of the National Recovery and Resilience Plan (NPOO), project “Eruptive processes on the Sun.” We acknowledge funding from the European Union’s Horizon Europe research and innovation program under grant agreement No. 101134999 (SOLER). The paper reflects only the authors’ view and the European Commission is not responsible for any use that may be made of the information it contains. The authors acknowledge financial support by the University of Graz.
