The Spheromak Tilting and How it Affects Modeling Coronal Mass Ejections

Spheromak-type flux ropes are increasingly used for modeling coronal mass ejections (CMEs). Many models aim at accurately reconstructing the magnetic field topology of CMEs, considering its importance in assessing their impact on modern technology and human activities in space and on the ground. How...

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Bibliographic Details
Published in:The Astrophysical journal 2022-02, Vol.926 (1), p.87
Main Authors: Asvestari, Eleanna, Rindlisbacher, Tobias, Pomoell, Jens, Kilpua, Emilia K. J.
Format: Article
Language:English
Subjects:
Astrophysics
Attitude (inclination)
Coronal mass ejection
Field strength
Helicity
Human influences
Interplanetary magnetic fields
Magnetic fields
Magnetic properties
Magnetic structure
Magnetohydrodynamical simulations
Modelling
Rotating spheres
Solar coronal mass ejections
Space weather
Spheromaks
Symmetry
Topology
Weather forecasting
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Summary:Spheromak-type flux ropes are increasingly used for modeling coronal mass ejections (CMEs). Many models aim at accurately reconstructing the magnetic field topology of CMEs, considering its importance in assessing their impact on modern technology and human activities in space and on the ground. However, so far there is little discussion about how the details of the magnetic structure of a spheromak affect its evolution through the ambient field in the modeling domain and what impact this has on the accuracy of magnetic field topology predictions. If the spheromak has its axis of symmetry (geometric axis) at an angle with respect to the direction of the ambient field, then the spheromak starts rotating so that its symmetry axis finally aligns with the ambient field. When using the spheromak in space weather forecasting models, this tilting can happen already during insertion and significantly affects the results. In this paper, we highlight this issue previously not examined in the field of space weather and we estimate the angle by which the spheromak rotates under different conditions. To do this, we generated simple purely radial ambient magnetic field topologies (weak/strong, positive/negative) and inserted spheromaks with varying initial speed, tilt, and magnetic helicity sign. We employ different physical and geometric criteria to locate the magnetic center of mass and axis of symmetry of the spheromak. We confirm that spheromaks rotate in all investigated conditions and their direction and angle of rotation depend on the spheromak’s initial properties and ambient magnetic field strength and orientation.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac3a73