Subject: coronal HXRs

From: Astrid Veronig <[email-masked]>
Date: Thu, 16 Jun 2005 16:19:32 +0200 (MEST)

Hugh, 

I was going trough your draft on coronal hard X-rays, and I liked it. 
Here are some comments from me:

The early-phase hard spectrum and early-phase "superhot" sources, I would 
think are maybe better described as "pre-impulsive" than "early-phase"?

I also wonder whether these should maybe be subsumed in one category,
since at the moment we do not have many samples for them (23 Jul 2003 and
the early 3rd Nov 2003 flare for the nonthermal and the later 3rd Nov 2003
flare for the "superhot" case). It might well be that maybe both
events are kind of similar (as usual, the spectra are not uniquely fitted
with one certain model). Maybe there could even come out something
more substantial than we have up to now when we start comparing these 
events. 
For the 23rd Jul flare you have evidence for nonthermal emission 
from Nobeyama data as far as I understood your discussion on the Asai et 
al. 2005 paper - that's of course good independent evidence. (By the 
way, is it possible to get a preprint of that paper?)

And most important: I have the impression that the events Laura is working
on and S. Kane (also Säm?) where coronal emission is detected up to 200
keV or so, should be there as a separate category. To me these seem to be
the most mysterious ones which require thinking beyond the usual lines. In
addition to collisional stopping (thin/thick target) there has to be
different physics involved (turbululence, or what ever) to understand
these observations. I think at the moment is totally unclear how
these sources can be in the corona. 

That's it for now, just sort of brain storming.

Astrid