[Loops] summaries on nanoflare debates in "coronalloopworkshops"

[Markus J. Aschwanden]

Dear Jim,

Ok, we agree we need heating of chromospheric material to fill coronal  
loops (i.e. the well-established
chromospheric evaporation scenario for flares), which is a kind of a  
secondary step. What we are not
sure is where is the primary energy release that leads up to the  
chromospheric heating:

(1) Is it in coronal reconnection sites that produces precipitating  
particles/donward conduction like in flares?
(2) Is it coronal nanoflares that could also produce precipitating  
particles and/or downward conduction?
(3) Is it reconnection events in the chromosphere/transition region

Since I see a continous transition from high-lying reconnection  
regions in large flares to low-lying
reconnection regions in microflares or EUV nanoflares, it appears  
natural to me that there is a
continuouity from (1) to (3). But do we need case (2), which was  
postulated by Parker ?
As long we do not have any observational measurements for case (2), it  
remains a
theoretical construct. So, what observational diagnostics can people  
come up to test case (2) ?

Markus



On Mar 6, 2009, at 11:11 AM, Klimchuk, James A. (GSFC-6710) wrote:

> Markus, you are definitely right that all coronal material  
> originates in the chromosphere.  If the energy release (heating)  
> occurs in the corona, a downward thermal conduction flux (and  
> possibly also a downward flux of nonthermal particles) causes  
> material to evaporate into the corona.   That is the traditional  
> view.  What other people (including you?) are proposing is that the  
> energy release occurs directly in the chromosphere or transition  
> region, and this process both heats the cool plasma and injects it  
> upward.
>
> Jim
>
> From: loops-bounces at solar.physics.montana.edu [mailto:loops-bounces at solar.physics.montana.edu 
> ] On Behalf Of Markus J. Aschwanden
> Sent: Friday, March 06, 2009 11:52 AM
> To: A mailing list for scientists involved in the observation and  
> modeling ofsolar loop structures
> Subject: Re: [Loops] summaries on nanoflare debates in  
> "coronalloopworkshops"
>
>
> On Mar 6, 2009, at 8:44 AM, Klimchuk, James A. (GSFC-6710) wrote:
>
>
>
> By the way, I do NOT believe that observations necessarily point to  
> low
> altitude heating.  My view is that observations are consistent with  
> both
> low altitude and high altitude heating.  Perhaps this should be a  
> topic
> for Loops IV.
>
> Jim
>
> There is no way around to heat up first chromospheric material to  
> fill coronal
> loops to produce the enhanced soft X-ray and EUV emission we see from
> coronal loops (like in flares). Any heating mechanism that heats  
> directly
> in the corona, does not increase the local density, so we would not  
> see
> any loops.
>
> Markus
>
>
>
> ____________________________________________
> Dr. Markus J. Aschwanden
> Solar & Astrophysics Laboratory
> Lockheed Martin Advanced Techology Center
> Org. ADBS, Bldg. 252
> 3251 Hanover St., Palo Alto, CA 94304, USA
> Phone: 650-424-4001, FAX: 650-424-3994
> URL: http://www.lmsal.com/~aschwand/
> e-mail: aschwanden at lmsal.com
> _______________________________________
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>
>
>
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____________________________________________
Dr. Markus J. Aschwanden
Solar & Astrophysics Laboratory
Lockheed Martin Advanced Techology Center
Org. ADBS, Bldg. 252
3251 Hanover St., Palo Alto, CA 94304, USA
Phone: 650-424-4001, FAX: 650-424-3994
URL: http://www.lmsal.com/~aschwand/
e-mail: aschwanden at lmsal.com
_______________________________________
____________________________________



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