Dear Friends,
Please find in the link a paper on Fan loops
that is just published in ApJ.
http://iopscience.iop.org/article/10.3847/1538-4357/835/2/244/pdf
Please let us know of any comments/suggestions you have on the paper.
For your information, I copied the abstract below:
Abstract: A comprehensive study of the
physical parameters of active region fan loops is
presented using the observations
recorded with the Interface Region Imaging Spectrometer
(IRIS), the EUV Imaging Spectrometer (EIS) on board
Hinode, and the Atmospheric Imaging
Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on
board the Solar Dynamics
Observatory (SDO). The fan loops emerging from non-flaring AR
11899 (near the disk
center)
on 2013 November 19 are clearly discernible in AIA 171 Å images
and in those obtained in
Fe VIII and
Si VII images using EIS. Our measurements of electron densities
reveal that the
footpoints of these loops are at an
approximately constant pressure with electron densities
of log Ne = 10.11 cm−3 at log [T/K ] T K = 5.15 (O IV), and
log Ne = 8.9 cm−3 at
log [T/K] = 6.15 (Si X). The electron temperature diagnosed
across the fan loops by means
of EM-Loci suggest that two temperature components exist at log
[T/K ] = 4.95 at the footpoints.
These
components are picked up by IRIS lines and EIS lines,
respectively. At higher heights, the loops
are nearly
isothermal at log [T/K ] = 5.95, which remained constant along
the loop. The measurement
of the Doppler shift
using IRIS lines suggests that the plasma at the footpoints of
these loops is
predominantly redshifted by 2–3 km s−1
in C II, 10–15 km s−1 in Si IV, and 15–20 km s−1 in O IV,
reflecting the increase in the speed of downflows with
increasing temperature from log [T/K ] = 4.40 to 5.15.
These observations can be explained by low-frequency
nanoflares or impulsive heating, and provide
further important constraints on the modeling of the dynamics of
fan
loops.
Best,
-Durgesh