Dear all,
the following paper has recently been accepted by ApJ Letters. You can
find a copy of the paper and relevant movies at
www.lmsal.com/~ptesta/hic_moss/
thanks,
Paola
title:
Observing coronal nanoflares in active region moss
authors:
P. Testa, B. De Pontieu, J. Martinez-Sykora, E. DeLuca, V. Hansteen, J.
Cirtain, A. Winebarger, L. Golub, K. Kobayashi, K. Korreck, S. Kuzin, R.
Walsh, C. DeForest, A. Title, M.Weber
abstract:
The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A
images of the upper transition region moss at an unprecedented spatial
(~0.3-0.4 arcsec) and temporal (5.5s) resolution.
The Hi-C observations show in some moss regions variability on
timescales down to ~15s, significantly shorter than the minute scale
variability typically found in previous observations of moss, therefore
challenging the conclusion of moss being heated in a mostly steady
manner. These rapid variability moss regions are located at the
footpoints of bright hot coronal loops observed by SDO/AIA in the 94A
channel, and by Hinode/XRT.
The configuration of these loops is highly dynamic, and suggestive of
slipping reconnection.
We interpret these events as signatures of heating events associated
with reconnection occurring in the overlying hot coronal loops, i.e.,
coronal nanoflares.
We estimate the order of magnitude of the energy in these events to be
of at least a few $10^{23}$~erg, also supporting the nanoflare scenario.
These Hi-C observations suggest that future observations at comparable
high spatial and temporal resolution, with more extensive temperature
coverage are required to determine the exact characteristics of the
heating mechanism(s).
Hello everyone,
Here are two new papers by Peter Cargill and me that may be of interest to
you.
The first "The influence of numerical resolution on coronal density in
hydrodynamic models of impulsive heating" takes what we believe to be a
long-overdue look at the issues surrounding the question of grid resolution
in numerical models and some of the physical implications of under-resolving
particular regions of the solar atmosphere. The paper has already been
published by ApJ and can be obtained here:
http://iopscience.iop.org/0004-637X/770/1/12/pdf/0004-637X_770_1_12.pdf
The second "The Cooling of Coronal Plasmas. iv: Catastrophic Cooling of
Loops" is a continuation of our series on the relevant cooling processes in
the solar atmosphere. Here we provide a physical explanation of the onset of
catastrophic cooling, which may provide an explanation for the relatively
weak active region emission detected in wavelength channels sensitive to
lower temperature lines. The manuscript has been accepted for publication by
ApJ and is available on astro-ph:
http://arxiv.org/ftp/arxiv/papers/1305/1305.5484.pdf
Hope to see many of you in Montana!
Best,
Steve
Dr Stephen J. Bradshaw
(Assistant Professor of Physics and Astronomy)
Department of Physics and Astronomy, MS-108,
Rice University,
6100 Main Street,
Houston,
TX 77005,
USA.
Tel: +1 713 348 4045
Email: stephen.bradshaw(a)rice.edu