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@solar.physics.montana.edu [mailto:loops- bounces@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@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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