<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Jim<div><br></div><div>I have some comments. It looks like a nice piece of work, but as usual the conclusion that only nanoflares can help is hopelessly quixotic. You set up a strawman competing mechanism (why call it "thermal nonequilibrium" when the one-syllable alternative "flow" works as well?) and reject it on the basis of time scales. Who knows about the time scales of the driver of the flows?</div><div><br></div><div>The model itself seems highly questionable. I had cited its predecessor in trying to explain the "chewy nougat" observation of X-rays from prominences (<a href="http://adsabs.harvard.edu/abs/1999ApJ...513L..83H">http://adsabs.harvard.edu/abs/1999ApJ...513L..83H</a>) but realized later on that the model has a very artificial low-temperature boundary and is thus not compelling. It is surprising to me that a decade later this has not changed, especially since it is just this boundary region in which the heating may be taking place.</div><div><br></div><div>To be perfectly clear about nanoflares: I do not think that there is any convincing observational evidence that they exist. It is a purely theoretical construct.</div><div><br></div><div>Cheers</div><div><br></div><div>Hugh</div><div><br></div><div>p.s. at the Hinode meeting just concluded, a nice poster by Helen Mason made it very clear that EIS spectra emphatically do not agree with the various XRT suggestions of a high-temperature component in the loop DEM. The discrepancy is an order of magnitude.</div><div><br><div><div>On 4 Dec 2009, at 14:04, Klimchuk, James A. (GSFC-6710) wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div lang="EN-US" link="blue" vlink="purple"><div class="Section1"><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Dear Loops Friends,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "> If you are interested, the attached paper shows that coronal loops cannot be explained by thermal nonequilibrium. The results appear to rule out the widespread existence of coronal heating that is both highly concentrated low in the corona and steady or quasi-steady (slowly varying or impulsive with a rapid cadence). Comments are welcomed.<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Best wishes,<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; ">Jim<o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><o:p> </o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: Arial, sans-serif; ">********************************************************************************</span><span style="font-size: 12pt; font-family: 'Times New Roman', serif; "><o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-bottom: 0.0001pt; margin-left: 0in; font-size: 11pt; font-family: Calibri, sans-serif; "><span style="font-size: 10pt; font-family: Arial, sans-serif; ">James A. 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