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.

25 pages, 5 figures, Accepted for Publication in The Astrophysical Journal

References in corpus (3)

• Flows and Motions in Moss in the Core of a Flaring Active Region: Evidence for Steady Heating
• Diagnosing the time-dependence of active region core heating from the emission measure: II. Nanoflare trains
• Doppler shift of hot coronal lines in a moss area of an active region

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• Electron Densities in the Solar Corona Measured Simultaneously in the Extreme-Ultraviolet and Infra-Red
• Transient Formation of Loops in the Core of an Active Region
• Properties of the diffuse emission around warm loops in solar active regions
• Formation and Dynamics of Transequatorial Loops