<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Dear all,<br>
<br>
you might be interested in the following paper that has just been
published on Science:<br>
"Evidence of non-thermal particles in coronal loops heated
impulsively by nanoflares"<br>
It can be downloaded from astro-ph: <a class="moz-txt-link-freetext" href="http://arxiv.org/abs/1410.6130">http://arxiv.org/abs/1410.6130</a>
or directly<br>
from the Science pages:
<a class="moz-txt-link-freetext" href="http://www.sciencemag.org/content/346/6207/1255724">http://www.sciencemag.org/content/346/6207/1255724</a><br>
The abstract is below.<br>
<br>
cheers,<br>
Paola<br>
<br>
<br>
Abstract:<br>
The physical processes causing energy exchange between the Sun’s hot
corona and its<br>
cool lower atmosphere remain poorly understood. The chromosphere and
transition region<br>
(TR) form an interface region between the surface and the corona
that is highly sensitive to<br>
the coronal heating mechanism. High-resolution observations with the
Interface Region<br>
Imaging Spectrograph (IRIS) reveal rapid variability (~20 to 60
seconds) of intensity and<br>
velocity on small spatial scales (≲500 kilometers) at the footpoints
of hot and dynamic<br>
coronal loops. The observations are consistent with numerical
simulations of heating by<br>
beams of nonthermal electrons, which are generated in small
impulsive (≲30 seconds)<br>
heating events called “coronal nanoflares.” The accelerated
electrons deposit a sizable<br>
fraction of their energy (≲10^25 erg) in the chromosphere and TR.
Our analysis provides tight<br>
constraints on the properties of such electron beams and new
diagnostics for their<br>
presence in the nonflaring corona.<br>
<meta charset="utf-8">
<br>
</body>
</html>