Hi Alan,

 We have two "cunning plans":

(1) there is a rocket proposal for a new grazing incident spectrograph - Ken Kobayashi, Leon, Jonathan or Kelly can provide more details.

(2) A group at GSFC has had some success with microcalorimeters for solar use. Simon Bandler and Jay may have additional comments on this. The baseline detector would give ~2ev spectral resolution from 0.5-6kev, with a high resolution inner array of 32x32 pixels (~2"/pixel on a rocket) and a lower resolution outer array. The development work has proceeded to the point that we are likely to propose a solar rocket this year for the microcalorimeter.

Both of these operate in the soft wavelength band where we can more easily see coronal heating.

Ed

On 6/9/11 7:56 AM, Alan Gabriel wrote:
A nice paper and an important contribution to the debate. But the jury is still out. We may never resolve this without real spectroscopic evidence of the very hot component. Where is our future spectroscopy coming from??

Alan Gabriel


Le 09/06/2011 10:52, Fabio Reale a écrit :
Dear colleagues
    please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:

http://arxiv.org/abs/1106.1591

The abstract is below.

Best regards
Fabio Reale

Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions

Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni
                               Peres, Leon Golub

Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.

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