Flare reconnection-driven magnetic field and Lorentz force variations at the Sun's surface
arXiv:1904.05447 · doi:10.3847/1538-4357/ab1b3d
Abstract
During eruptive flares, vector magnetograms show increasing horizontal magnetic field and downward Lorentz force in the Sun's photosphere around the polarity-inversion line. Such behavior has often been associated with the implosion conjecture and interpreted as the result of either momentum conservation while the eruption moves upward, or of the contraction of flare loops. We characterize the physical origin of these observed behaviors by analyzing a generic 3D MHD simulation of an eruptive flare. Even though the simulation was undesigned to recover the magnetic field and Lorentz force properties, it is fully consistent with them, and it provides key additional informations to understand them. The area where the magnetic field increases gradually develops between current ribbons, which spread away from each other and are connected to the coronal region. This area is merely the footprint of the coronal post-flare loops, whose contraction increases their shear field component and the magnetic energy density in line with the ideal induction equation. For simulated data, we computed the Lorentz force density map by applying the method used in observations. We obtained increase of the downward component of the Lorentz force density around the PIL -consistent with observations. However, this significantly differs from the Lorentz force density maps obtained directly from the 3D magnetic field and current. These results altogether question previous interpretations based on the implosion conjecture and momentum conservation with the CME, and rather imply that the observed increases in photospheric horizontal magnetic fields result from the reconnection-driven contraction of sheared flare-loops.
arXiv comment20 pages, 11 figures, accepted for publication in ApJ (April 19, 2019)
References in corpus (23)
- Evolution of Magnetic Field and Energy in A Major Eruptive Active Region Based on SDO/HMI Observation
- The standard flare model in three dimensions III. Slip-running reconnection properties
- Electric current in flares ribbons: observations and 3D standard model
- Global Properties of Solar Flares
- Response of the Photospheric Magnetic Field to the X2.2 Flare on 2011 February 15
- Observational Evidence of Back-reaction on the Solar Surface Associated with Coronal Magnetic Restructuring in Solar Eruptions
- Critical decay index at the onset of solar eruptions
- Drifting of the line-tied footpoints of CME flux-ropes
- Rapid Changes of Photospheric Magnetic Field after Tether-Cutting Reconnection and Magnetic Implosion
- Abrupt changes in photospheric magnetic and Lorentz-force vectors during neutral-line flares
- Evolution of Flare Ribbons, Electric Currents and Quasi-separatrix Layers During an X-class Flare
- Evidence for collapsing fields in corona and photosphere during the 15 February 2011 X2.2 flare: SDO AIA and HMI Observations
- Investigating the Magnetic Imprints of Major Solar Eruptions with SDO/HMI High-Cadence Vector Magnetograms
- A spatio-temporal description of the abrupt changes in the photospheric magnetic and Lorentz-force vectors during the 2011 February 15 X2.2 flare
- First Detection of Chromospheric Magnetic Field Changes During an X1-Flare
- A unified view of coronal loop contraction and oscillation in flares
- Three-dimensional Magnetic Restructuring in Two Homologous Solar Flares in the Seismically Active NOAA AR 11283
- Thermal signatures of tether-cutting reconnections in pre-eruption coronal flux ropes: hot central voids in coronal cavities
- A Comparative Study of the Eruptive and Non-Eruptive Flares Produced by the Largest Active Region of Solar Cycle 24
- Vortex and sink flows in eruptive flares as a model for coronal implosions
- Evolution of Photospheric Vector Magnetic Field Associated with Moving Flare Ribbons As Seen By GST
- Expanding and Contracting Coronal Loops as Evidence of Vortex Flows Induced by Solar Eruptions
- Photospheric response to a flare
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- The European Solar Telescope
- Observation of all pre- and post-reconnection structures involved in three-dimensional reconnection geometries in solar eruptions
- The role of small-scale surface motions in the transfer of twist to a solar jet from a remote stable flux rope
- Partial Eruption, Confinement, and Twist Buildup and Release of a Double-decker Filament
- Electric current evolution at the footpoints of solar eruptions
- A statistical Analysis of Magnetic Field Changes in the Photosphere During Solar Flares Using High-cadence Vector Magnetograms and Their Association with Flare Ribbons
- Energy and helicity fluxes in line-tied eruptive simulations
- Filament Leg--Leg Reconnection as a Source of Prominent Supra-Arcade Downflows
- On the nature of photospheric horizontal magnetic field increase in major solar flares
- Continuum enhancements, line profiles and magnetic field evolution during consecutive flares
- How flux feeding causes eruptions of solar magnetic flux ropes with the hyperbolic flux tube configuration?
- Erupting Magnetic Flux Rope Affects Running Penumbral Waves
- Photospheric Lorentz force changes in eruptive and confined solar flares
- Back Reaction of the Untwisting Solar Corona Scars Sunspots