Imaging and Spectroscopic Observations of a Transient Coronal Loop: Evidence for the Non-Maxwellian $\kappa$-Distributions

Abstract

We report on the SDO/AIA and Hinode/EIS observations of a transient coronal loop. The loop brightens up in the same location after the disappearance of an arcade formed during a B8.9-class microflare three hours earlier. EIS captures this loop during its brightening phase as observed in most of the AIA filters. We use the AIA data to study the evolution of the loop, as well as to perform the DEM diagnostics as a function of $\kappa$. Fe XI--XIII lines observed by EIS are used to perform the diagnostics of electron density and subsequently the diagnostics of $\kappa$. Using ratios involving the Fe XI 257.772Åselfblend, we diagnose $\kappa$ $\lesssim$ 2, i.e., an extremely non-Maxwellian distribution. Using the predicted Fe line intensities derived from the DEMs as a function of $\kappa$, we show that, with decreasing $\kappa$, all combinations of ratios of line intensities converge to the observed values, confirming the diagnosed $\kappa$ $\lesssim$ 2. These results represent the first positive diagnostics of $\kappa$-distributions in the solar corona despite the limitations imposed by calibration uncertainties.

arXiv commentThe Astrophysical Journal, accepted

References in corpus (28)

• The Interface Region Imaging Spectrograph (IRIS)
• On Solving the Coronal Heating Problem
• Differential Emission Measures from the Regularized Inversion of Hinode and SDO data
• Evidence of Non-Thermal Particles in Coronal Loops Heated Impulsively by Nanoflares
• High precision density measurements in the solar corona: I. Analysis methods and results for Fe XII and Fe XIII
• A Systematic Survey of High Temperature Emission in Solar Active Regions
• Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIA
• The Formation of Kappa-Distribution Accelerated Electron Populations in Solar Flares
• Multi-thermal dynamics and energetics of a coronal mass ejection in the low solar atmosphere
• A revised radiometric calibration for the Hinode/EIS instrument
• Patterns of Nanoflare Storm Heating Exhibited by an Active Region Observed with SDO/AIA
• Can Thermal Nonequilibrium Explain Coronal Loops?
• On-Orbit Degradation of Solar Instruments
• Particle acceleration and transport in reconnecting twisted loops in a stratified atmosphere
• The Absolute Calibration of the EUV Imaging Spectrometer on Hinode
• Diagnosing the time-dependence of active region core heating from the emission measure: I. Low-frequency nanoflares
• Solar Transition-Region Lines Observed by the Interface Region Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
• KAPPA: A Package for Synthesis of optically thin spectra for the non-Maxwellian kappa-distributions based on the CHIANTI database
• Modeling the Line-of-Sight Integrated Emission in the Corona: Implications for Coronal Heating
• H to Zn Ionization Equilibrium for the Non-Maxwellian Electron kappa-distributions: Updated Calculations
• Constraining the hard X-ray properties of the quiet Sun with new RHESSI observations
• Ion Charge States in the Fast Solar Wind: New Data Analysis and Theoretical Refinements
• Effect of collisions and magnetic convergence on electron acceleration and transport in reconnecting twisted solar flare loops
• Evidence of Impulsive Heating in Active Region Core Loops
• Solar Particle Acceleration at Reconnecting 3D Null Points
• Signatures of the non-Maxwellian $\kappa$-distributions in optically thin line spectra \subtitle{I. Theory and synthetic Fe IX--XIII spectra}
• Are Coronal Loops Isothermal or Multithermal? Yes!
• Underflight calibration of SOHO/CDS and Hinode/EIS with EUNIS-07

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• Solar coronal lines in the visible and infrared. A rough guide
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• Non-Maxwellian analysis of the transition-region line profiles observed by the Interface Region Imaging Spectrograph
• A Simple Method for Modeling Collision Processes in Plasmas with a Kappa Energy Distribution
• The CHIANTI atomic database
• Spectroscopic diagnostics of the non-Maxwellian $\kappa$-distributions using SDO/EVE observations of the 2012 March 7 X-class flare
• Signatures of the non-Maxwellian $\kappa$-distributions in optically thin line spectra. II. Synthetic Fe XVII--XVIII X-ray coronal spectra and predictions for the Marshall Grazing-Incidence X-ray Spectrometer (MaGIXS)
• Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red
• Non-equilibrium ionization by a periodic electron beam. I. Synthetic coronal spectra and implications for interpretation of observations
• Non-equilibrium ionization by a periodic electron beam II. Synthetic Si IV and O IV transition region spectra
• X-ray Spectra from Plasmas with High-Energy Electrons: kappa-distributions and e-e Bremsstrahlung
• Can the Kappa-distributed electron energies account for the intensity ratios of O II lines in photoionized gaseous nebulae?
• Multi-diagnostic convergence: a single measurement in weakly collisional plasmas
• A benchmark of the He-like triplet for ions with $6\le Z\le 14$ in Maxwellian and non-Maxwellian plasmas
• Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution