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,
We were informed that "your manuscript, "Prominence-cavity regions
observed using SWAP 174A filtergrams and simultaneous eclipse flash
spectra", by Bazin, C. Koutchmy, S. and Tavabi, E. has been accepted for
publication in Solar Physics."
A preprint is available at:
http://arxiv.org/abs/1207.1857
Note it is the 1st time that prominences and the so-called cavity often
seen above eclipse prominences are analyzed using a high spectral
resolution near the HeI and the HeII lines simultaneously with high S/N
ratio SWAP filtergrams at 174A and with EIT filtergrams, shedding some
light on the prominence-corona interacting region physics.
Please find after an abstract of the paper.
Feel free to contact the authors in case some additional material is
needed.
Enjoy!
Best,
Serge
-------------------------------------------------------------
At the occasion of the last solar total eclipse of 11th July, 2010, we
studied SWAP filtergrams (from the PROBA2 mission) taken at 17.4 nm in
the Fe IX/X lines with simultaneous slitless flash spectra in the
spectral region of 470 nm. These eclipse flash spectra showed many faint
low excitation emission lines with He I 471.3 nm and He II 468.6 nm
Paschen {\alpha} chromospheric lines, and correspond to off-limb
prominences regions observed with space-borne imagers. We aligned and
stacked 80 individual spectra to study some modulations intensities
along the continuum between the monochromatic images of the prominences
without parasitic scattered light. We observed intensity depressions
around the continuum between prominences in both eclipse and SWAP
images. The prominence cavities are associated with a depression of the
plasma density, produced in the interface regions between the corona and
the prominences. Photometric measurements are shown at different scales
and different narrow spectral intervals, for both the prominences and
the coronal background.
Comments: 20 pages, 15 figures.
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