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<div class="">Dear Loop Enthusiasts,</div>
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<div class="">I would like to draw your attention to our paper that was recently accepted to ApJ, and has been posted to arXiv (<a href="https://arxiv.org/abs/1706.06108" class="">https://arxiv.org/abs/1706.06108</a>):</div>
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<div class="">See you in Palermo!</div>
<div class="">Paul</div>
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<div class=""><b class="">Microflare Heating of a Solar Active Region Observed with <i class="">NuSTAR</i>, <i class="">Hinode</i>/XRT, and <i class="">SDO</i>/AIA</b></div>
<div class=""><a href="https://arxiv.org/abs/1706.06108" class="">https://arxiv.org/abs/1706.06108</a></div>
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<div class="">Paul J. Wright, Iain G. Hannah, Brian W. Grefenstette, Lindsay Glesener, </div>
<div class="">Sam Krucker, Hugh S. Hudson, David M. Smith, Andrew J. Marsh, Stephen M. White, Matej Kuhar</div>
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<div class="">ABSTRACT: <i class="">NuSTAR</i> is a highly sensitive focusing hard X-ray (HXR) telescope and has observed several small microflares in its initial solar pointings. In this paper, we present the first joint observation of a microflare with <i class="">NuSTAR</i> and <i class="">Hinode</i>/XRT
on 2015 April 29 at ~11:29 UT. This microflare shows heating of material to several million Kelvin, observed in Soft X-rays (SXRs) with <i class="">Hinode</i>/XRT, and was faintly visible in Extreme Ultraviolet (EUV) with <i class="">SDO</i>/AIA. For three
of the four <i class="">NuSTAR</i> observations of this region (pre-, decay, and post phases) the spectrum is well fitted by a single thermal model of 3.2 - 3.5 MK, but the spectrum during the impulsive phase shows additional emission up to 10 MK, emission
equivalent to A0.1 <i class="">GOES</i> class. We recover the differential emission measure (DEM) using <i class="">SDO</i>/AIA, <i class="">Hinode</i>/XRT, and <i class="">NuSTAR</i>, giving unprecedented coverage in temperature. We find the pre-flare DEM
peaks at ~ 3 MK and falls off sharply by 5 MK; but during the microflare's impulsive phase the emission above 3 MK is brighter and extends to 10 MK, giving a heating rate of about 2.5 x 10^25 erg/s. As the <i class="">NuSTAR</i> spectrum is purely thermal
we determined upper-limits on the possible non-thermal bremsstrahlung emission. We find that for the accelerated electrons to be the source of the heating requires a power-law spectrum of $\delta \ge 7$ with a low energy cut-off $E_{c} \lesssim 7$ keV. In
summary, this first <i class="">NuSTAR</i> microflare strongly resembles much more powerful flares.</div>
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-----<br class="">
Paul J. Wright<br class="">
Solar Physics Ph.D. Candidate<br class="">
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Rm 614 Kelvin Building,<br class="">
School of Physics and Astronomy,<br class="">
University of Glasgow<br class="">
Glasgow<br class="">
G12 8QQ<br class="">
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E: <a href="mailto:paul.wright@glasgow.ac.uk" class="">paul.wright@glasgow.ac.uk</a><br class="">
W: <a href="http://www.pauljwright.co.uk" class="">www.pauljwright.co.uk</a></div>
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E (permanent): <a href="mailto:paul@pauljwright.co.uk" class="">paul@pauljwright.co.uk</a><br class="">
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