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<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif"">Dear Colleagues,
<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif"">We have just published a new paper: Viall, N. M. & Klimchuk, J. A., 'The Transition Region Response to a Coronal Nanoflare: Forward Modeling and Observations in SDO/AIA', 2015,
<span style="color:black;background:white">ApJ, 799, 58.</span><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif"">It can be found here<span style="color:#1F497D">:
</span><a href="http://stacks.iop.org/0004-637X/799/58">http://stacks.iop.org/0004-637X/799/58</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif";color:black;background:white">Abstract: The corona and transition region (TR) are fundamentally coupled through the processes of thermal conduction and mass exchange. It is not possible
to understand one without the other. Yet the temperature-dependent emissions from the two locations behave quite differently in the aftermath of an impulsive heating event such as a coronal nanoflare. Whereas the corona cools sequentially, emitting first at
higher temperatures and then at lower temperatures, the TR is multithermal and the emission at all temperatures responds in unison. We have previously applied the automated time lag technique of Viall & Klimchuk to disk observations of an active region (AR)
made by the Atmospheric Imaging Assembly (AIA) on the<span class="apple-converted-space"> </span><i>Solar Dynamics Observatory</i>. Lines of sight passing through coronal plasma show clear evidence for post-nanoflare cooling, while lines of sight intersecting
the TR footpoints of coronal strands show zero time lag. In this paper, we use the EBTEL hydrodynamics code to demonstrate that this is precisely the expected behavior when the corona is heated by nanoflares. We also apply the time lag technique for the first
time to off-limb observations of an AR. Since TR emission is not present above the limb, the occurrence of zero time lags is greatly diminished, supporting the conclusion that zero time lags measured on the disk are due to TR plasma. Lastly, we show that the
''coronal'' channels in AIA can be dominated by bright TR emission. When defined in a physically meaningful way, the TR reaches a temperature of roughly 60% the peak temperature in a flux tube. The TR resulting from impulsive heating can extend to 3 MK and
higher, well within the range of the ''coronal'' AIA channels.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif"">Cheers,
<o:p></o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif""><o:p> </o:p></span></p>
<p class="MsoPlainText"><span style="font-family:"Times New Roman","serif"">Nicki<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Garamond","serif";color:#000099">***************************<br>
</span><span style="font-size:10.0pt;font-family:"Garamond","serif";color:#000099">Nicholeen M. Viall
<br>
Research Astrophysicist<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Garamond","serif";color:#000099">Solar Physics Laboratory<br>
Code 671<br>
NASA Goddard Space Flight Center<br>
Greenbelt, MD 20771<br>
V: 301-286-4054<br>
F: 301-286-7194<br>
Nicholeen.M.Viall@nasa.gov</span><span style="font-family:"Garamond","serif";color:#000099"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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