Solar low-lying cool loops and their contribution to the transition region EUV output

Abstract

In the last 30 years, the existence of small and cool magnetic loops (height < 8 Mm, T < 10^5 K) has been proposed and debated to explain the increase of the DEM (differential emission measure) towards the chromosphere. We present hydrodynamic simulations of low-lying cool loops to study their conditions of existence and stability, and their contribution to the transition region EUV output. We find that stable, quasi-static cool loops (with velocities < 1 km/s) can be obtained under different and more realistic assumptions on the radiative losses function with respect to previous works. A mixture of the DEMs of these cool loops plus intermediate loops with temperatures between 10^5 and 10^6 K can reproduce the observed emission of the lower transition region at the critical turn-up temperature point (T ~ 2x10^5 K) and below T = 10^5 K.

arXiv commentAccepted for publication in A&A on Nov 25th 2011

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Cited by in corpus (9)

• Structure of solar coronal loops: from miniature to large-scale
• Cool transition region loops observed by the Interface Region Imaging Spectrograph
• The solar chromosphere observed at 1 Hz and 0."2 resolution
• Miniature loops in the solar corona
• Plasma flows in the cool loop systems
• Explaining Inverted Temperature Loops in the Quiet Solar Corona with Magnetohydrodynamic Wave Mode Conversion
• Probing the quiet solar atmosphere from the photosphere to the corona
• The nature of small scale EUV solar brightenings investigated as impulsive heating of short loops in 1D hydrododynamics simulations
• Modelling solar low-lying cool loops with optically thick radiative losses