Undetected Minority-polarity Flux as the Missing Link in Coronal Heating

Abstract

During the last few decades, the most widely favored models for coronal heating have involved the in situ dissipation of energy, with footpoint shuffling giving rise to multiple current sheets (the "nanoflare" model) or to Alfv{é}n waves that leak into the corona and undergo dissipative interactions (the wave heating scenario). As has been recognized earlier, observations suggest instead that the energy deposition is concentrated at very low heights, with the coronal loops being filled with hot, dense material from below, which accounts for their overdensities and flat temperature profiles. While an obvious mechanism for footpoint heating would be reconnection with small-scale fields, this possibility seems to have been widely ignored because magnetograms show almost no minority-polarity flux inside active region (AR) plages. Here, we present further examples to support our earlier conclusions (1) that magnetograms greatly underrepresent the amount of minority-polarity flux inside plages and "unipolar" network, and (2) that small loops are a major constituent of \ion{Fe}{9} 17.1 nm moss. On the assumption that the emergence or churning rate of small-scale flux is the same inside plages as in mixed-polarity regions of the quiet Sun, we estimate the energy flux density associated with reconnection with the plage fields to be on the order of 10${}^7$ erg cm${}^{-2}$ s${}^{-1}$, sufficient to heat the AR corona.

References in corpus (24)

• On the Generation, Propagation, and Reflection of Alfven Waves from the Solar Photosphere to the Distant Heliosphere
• Heating of the Solar Chromosphere and Corona by Alfven Wave Turbulence
• Solar Coronal Jets: Observations, Theory, and Modeling
• Dynamic Fibrils are driven by Magnetoacoustic Shocks
• A Contemporary View of Coronal Heating
• Extreme UV quiet Sun brightenings observed by Solar Orbiter/EUI
• Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE
• Observables Processing for the Helioseismic and Magnetic Imager Instrument on the Solar Dynamics Observatory
• Seething Horizontal Magnetic Fields in the Quiet Solar Photosphere
• A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating
• Active region transition region loop populations and their relationship to the corona
• Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields
• Can the Solar Wind be Driven by Magnetic Reconnection in the Sun's Magnetic Carpet?
• Small-scale Flux Emergence, Coronal Hole Heating, and Flux-tube Expansion: A Hybrid Solar Wind Model
• The frontier between Small-scale bipoles and Ephemeral Regions in the solar photosphere: Emergence and Decay of an Intermediate-scale bipole observed with IMaX/SUNRISE
• Comparison of Magnetic Flux Distribution between a Coronal Hole and a Quiet Region
• Inference of the chromospheric magnetic field configuration of solar plage using the Ca II 8542 Å line
• Estimating the Chromospheric Absorption of Transition Region Moss Emission
• A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating III. 3D Simulations and Atmospheric Response
• Measurements of Photospheric and Chromospheric Magnetic Field Structures Associated with Chromospheric Heating over a Solar Plage Region
• Resonant absorption in expanding coronal magnetic flux tubes with uniform density
• The Evolution of Dark Canopies Around Active Regions
• Spatial Nonlocality of the Small-Scale Solar Dynamo
• Further Evidence for Looplike Fine Structure inside "Unipolar" Active Region Plages

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• Assessing the capability of a model-based stellar XUV estimation