The Magnetic Properties of Heating Events on High-Temperature Active Region Loops

Abstract

Understanding the relationship between the magnetic field and coronal heating is one of the central problems of solar physics. However, studies of the magnetic properties of impulsively heated loops have been rare. We present results from a study of 34 evolving coronal loops observed in the Fe XVIII line component of AIA/SDO 94 A filter images from three active regions with different magnetic conditions. We show that the peak intensity per unit cross-section of the loops depends on their individual magnetic and geometric properties. The intensity scales proportionally to the average field strength along the loop ($B_{avg}$) and inversely with the loop length ($L$) for a combined dependence of $(B_{avg}/L{)}^{0.52\pm 0.13}$. These loop properties are inferred from magnetic extrapolations of the photospheric HMI/SDO line-of-sight and vector magnetic field in three approximations: potential and two Non Linear Force-Free (NLFF) methods. Through hydrodynamic modeling (EBTEL model) we show that this behavior is compatible with impulsively heated loops with a volumetric heating rate that scales as ${\epsilon }_H\sim B_{avg}^{0.3\pm 0.2}/L^{0.2{\pm }_{0.1}^{0.2}}$.

Astrophysical Journal, in press

References in corpus (13)

• Highly Efficient Modeling of Dynamic Coronal Loops
• Observing the Roots of Solar Coronal Heating - in the Chromosphere
• Key Aspects of Coronal Heating
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• Observations of Active Region Loops with the EUV Imaging Spectrometer on Hinode
• Long-Period Intensity Pulsations in Coronal Loops Explained by Thermal Non-Equilibrium Cycles
• 3D MHD modeling of twisted coronal loops
• Modeling X-ray Loops and EUV "Moss" in an Active Region Core
• Inference of Heating Properties from "Hot" Non-flaring Plasmas in Active Region Cores. II. Nanoflare Trains
• Plasma parameters and geometry of cool and warm active region loops
• The temporal evolution of coronal loops observed by GOES-SXI
• New Evidence that Magnetoconvection Drives Solar-Stellar Coronal Heating
• Modeling Coronal Response in Decaying Active Regions with Magnetic Flux Transport and Steady Heating

Cited by in corpus (5)

• IRIS observations of short-term variability in moss associated with transient hot coronal loops
• Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops
• Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red
• Coronal Heating Law Constrained by Microwave Gyroresonant Emission
• Are the brightest coronal loops always rooted in mixed-polarity magnetic flux?