Emission Measure Distribution for Diffuse Regions in Solar Active Regions

Abstract

Our knowledge of the diffuse emission that encompasses active regions is very limited. In the present paper we investigate two off-limb active regions, namely AR10939 and AR10961, to probe the underlying heating mechanisms. For this purpose we have used spectral observations from Hinode/EIS and employed the emission measure (EM) technique to obtain the thermal structure of these diffuse regions. Our results show that the characteristic EM distributions of the diffuse emission regions peak at log T = 6.25 and the cool-ward slopes are in the range 1.4 - 3.3. This suggests that both low as well as high frequency nanoflare heating events are at work. Our results provide additional constraints on the properties of these diffuse emission regions and their contribution to the background/foreground when active region cores are observed on-disk.

arXiv comment25 pages, 5 figures, Accepted for Publication in The Astrophysical Journal

References in corpus (20)

• EUV emission lines and diagnostics observed with Hinode/EIS
• A Systematic Survey of High Temperature Emission in Solar Active Regions
• Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly
• On active region loops: Hinode/EIS observations
• Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model
• A revised radiometric calibration for the Hinode/EIS instrument
• Patterns of Nanoflare Storm Heating Exhibited by an Active Region Observed with SDO/AIA
• Active region transition region loop populations and their relationship to the corona
• Emission Measure Distribution and Heating of Two Active Region Cores
• Diagnosing the time-dependence of active region core heating from the emission measure: I. Low-frequency nanoflares
• The Temperature Dependence of Solar Active Region Outflows
• Velocity measurements for a solar active region fan loop from Hinode/EIS observations
• Modeling the Line-of-Sight Integrated Emission in the Corona: Implications for Coronal Heating
• Flows and Motions in Moss in the Core of a Flaring Active Region: Evidence for Steady Heating
• Can the Differential Emission Measure constrain the timescale of energy deposition
• Active Region Moss: Basic physical parameters and their temporal variation
• Diagnosing the time-dependence of active region core heating from the emission measure: II. Nanoflare trains
• Evidence of Impulsive Heating in Active Region Core Loops
• Active Region Moss: Doppler Shifts from Hinode/EIS Observations
• Doppler shift of hot coronal lines in a moss area of an active region

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• Fan Loops Observed by IRIS, EIS and AIA
• Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red
• On the Impulsive Heating of Quiet Solar Corona
• Transient Formation of Loops in the Core of an Active Region
• Non-equilibrium ionization by a periodic electron beam. I. Synthetic coronal spectra and implications for interpretation of observations
• A 7~MK hot Flux Rope Observed by SDO/AIA
• Properties of the diffuse emission around warm loops in solar active regions
• Formation and Dynamics of Transequatorial Loops
• On the Effect of Coronal Rain on Decayless Kink Oscillations of Coronal Loops
• Solar Atmospheric Magnetic Energy Coupling: Broad Plasma Conditions and Spectrum Regimes