[Loops] FW: summaries on nanoflare debatesin "coronalloopworkshops"

[Klimchuk, James A. (GSFC-6710)]

Arnold,

     Thanks to both you and David for your valuable input.  I have a
quick comment, just to make sure no one misinterprets what you wrote.
The events that you and Sam detected account for about 12% of the
radiated output in the quiet Sun.  The remainder of the radiated output
could be produced by smaller events that cannot be individually
detected.  Here's an interesting tidbit:  If nanoflares have an energy
of 10^24 erg (it could be smaller), they must occur at a rate of about
one per second in each coronal loop to satisfy the energy requirements.
That's awfully tough to detect, especially when you consider that the
cooling timescale is of order 100+ seconds!

Thanks again,
Jim

> -----Original Message-----
> From: loops-bounces at solar.physics.montana.edu [mailto:loops-
> bounces at solar.physics.montana.edu] On Behalf Of Arnold Benz
> Sent: Thursday, March 12, 2009 4:52 PM
> To: A mailing list for scientists involved in the observation and
modeling ofsolar
> loop structures
> Subject: Re: [Loops] FW: summaries on nanoflare debatesin
> "coronalloopworkshops"
> 
> 
> Dear David,
> 
> Welcome back! Indeed you did leave the nanoflare business some time
ago,
> when we realized that we will never agree on power-law exponents
because
> as you described there is a subjective element in the definition of a
> nanoflare. I fully agree with you, David, that power-law indices are
> useless and that we must not extrapolate them.
> However, power-laws are not the only way to evaluate nanoflares.  In
the
> mean time we have tried to estimate the energy input by the observed
> events. For this estimate, the distribution is not needed, just sum
over
> all events and pixels. The observed energy in the soft X-rays and EUV
> events at peak flux is about 12% of the radiated output in the quiet
sun
> (Benz & Krucker 2002). This includes only observed events above 5
10^24
> erg. What we measure, however, is the thermal energy at one instant of
> the event. This thermal energy is not the flare energy, but the result
> of precipitating particles heating the chromosphere. The particle
> acceleration is not the flare either, but arguably the result of waves
> that have been excited by the reconnection process (e.g. transit-time
> damping). Thus the real difficulty is to estimate the total energy
input
> into the corona from the observed nanoflares.
> 
> Regards,
> Arnold
> 
> __________________________________________________________________
> ______
> Arnold Benz
> Institute of Astronomy              email benz at astro.phys.ethz.ch
> ETH Zurich,  HIT J 23.1              voice ++41-44-632 42 23
> CH-8093 Zurich                           fax ++41-44-862 68 25
> Switzerland    web http://www.astro.phys.ethz.ch/staff/benz/benz.html
> __________________________________________________________________
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> 
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