Energetics of magnetic transients in a solar active region plage

Abstract

Densely packed coronal loops are rooted in plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plages are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in plages using high resolution observations and simulations. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the SST. These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the EUV emission maps obtained from the SDO/AIA. To obtain better insight into the evolution of plages, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. The observations show transient magnetic flux emergence and cancellation events within the plage on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m${}^{-2}$ through the photosphere. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

Published in A&A (abridged abstract)

References in corpus (13)

• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• A solar surface dynamo
• CRISPRED: A data pipeline for the CRISP imaging spectropolarimeter
• Magneto-convection in a sunspot umbra
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• Magnetic flux emergence in granular convection: Radiative MHD simulations and observational signatures
• Emergence of small-scale magnetic loops through the quiet solar atmosphere
• Transient horizontal magnetic fields in solar plage regions
• Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun
• Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields
• Properties of solar plage from a spatially coupled inversion of Hinode SP data
• Compact solar UV burst triggered in a magnetic field with a fan-spine topology
• A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating II. 2D Theory and Simulations

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• Data-driven model of the solar corona above an active region
• Impulsive coronal heating during the interaction of surface magnetic fields in the lower solar atmosphere
• NuSTAR observations of a repeatedly microflaring active region
• Further Evidence for Looplike Fine Structure inside "Unipolar" Active Region Plages
• Spectroscopic and imaging observations of transient hot and cool loops by IRIS and SDO
• Spectroscopic observation of a transition region network jet
• Photospheric Hot Spots at Solar Coronal Loop Footpoints Revealed by Hyperspectral Imaging Observations
• Active region upflows in various coronal structures and their coupling to the lower atmosphere
• Three-dimensional non-LTE radiative transfer effects in Fe I lines IV. Line formation at high spatial resolution