Hi everyone,
In the spirit of a number of recent papers that have been focused on trying
to determine the dominant components of the emission in the wavelength
channels of imaging instruments (AIA, in particular), Jim and I would like
to share with you all a link to a paper on this very topic that was recently
published in the ApJ Supplement Series:
http://iopscience.iop.org/0067-0049/194/2/26/pdf/apjs_194_2_26.pdf
Our aim in carrying out the work described in this paper was to provide a
large amount of quantitative data from our modeling studies that we hope
will be of use in the analysis of observationally gathered data.
Best wishes,
Steve
-----Original Message-----
From: loops-bounces(a)solar.physics.montana.edu
[mailto:loops-bounces@solar.physics.montana.edu] On Behalf Of Paola Testa
Sent: Tuesday, September 20, 2011 10:00 AM
To: A mailing list for scientists involved in the observation and modeling
of solar loop structures
Cc: Juan Martinez Sykora
Subject: [Loops] Forward modeling of emission in SDO/AIA passbands from
dynamic 3D simulations
Hello all,
here is a link to a preprint of a paper, accepted for publication on ApJ,
that is also discussing issues related to the interpretation of AIA
observations:
http://adsabs.harvard.edu/abs/2011arXiv1109.0704M
cheers,
Paola
On 9/9/11 12:03 PM, Giulio Del Zanna wrote:
>
> Dear colleagues,
>
> here is a link to a preprint that discusses various
> (important) issues related to the interpretation of AIA data:
>
> http://solar.physics.montana.edu/cgi-bin/eprint/index.pl?entry=15555
>
> Those of you that were present at the excellent Mallorca meeting might
> recall the issues we raised there. The paper, which follows on from
> O'Dwyer et al., contains more.
>
> I encourage all to follow the example in the Appendix to calculate
> your own AIA responses using CHIANTI. We will soon release v.7, but do
> not expect huge differences.
> We are working to try and improve the atomic data for AIA, more to come.
>
>
> best wishes,
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Dear all,
A new paper concerning the time-dependence of active region heating based on emission measures has just been published in ApJ.
Diagnosing the time-dependence of active region core heating from the emission measure. I. Low-frequency nanoflares
Bradshaw, S. J., Klimchuk, J. A., & Reep, J. W. 2012, ApJ, 758, 53
http://iopscience.iop.org/0004-637X/758/1/53/pdf/0004-637X_758_1_53.pdf
Abstract:
Observational measurements of active region emission measures contain clues to the time dependence of the underlying heating mechanism. A strongly nonlinear scaling of the emission measure with temperature indicates a large amount of hot plasma relative to warm plasma. A weakly nonlinear (or linear) scaling of the emission measure indicates a relatively large amount of warm plasma, suggesting that the hot active region plasma is allowed to cool and so the heating is impulsive with a long repeat time. This case is called low-frequency nanoflare heating, and we investigate its feasibility as an active region heating scenario here.We explore a parameter space of heating and coronal loop properties with a hydrodynamic model. For each model run, we calculate the slope α of the emission measure distribution EM(T ) ∝ T α. Our conclusions are: (1) low-frequency nanoflare heating is consistent with about 36% of observed active region cores when uncertainties in the atomic data are not accounted for; (2) proper consideration of uncertainties yields a range in which as many as 77% of observed active regions are consistent with low-frequency nanoflare heating and as few as zero; (3) low-frequency nanoflare heating cannot explain observed slopes greater than 3; (4) the upper limit to the volumetric energy release is in the region of 50 erg cm−3 to avoid unphysical magnetic field strengths; (5) the heating timescale may be short for loops of total length less than 40Mm to be consistent with the observed range of slopes; (6) predicted slopes are consistently steeper for longer loops.
Best wishes,
Steve
Dr Stephen J. Bradshaw
Department of Physics and Astronomy, MS-108,
Rice University,
6100 Main Street,
Houston,
TX 77005,
USA.
Tel: +1 713 348 4045
Email: stephen.bradshaw(a)rice.edu