C. Sasso, V. Andretta, D. Spadaro, R. Susino
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.
View original:
http://arxiv.org/abs/1112.0309
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