This page (revision-83) was last changed on 02-Feb-2017 13:19 by David R Williams

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At line 361 added one line
Then we compared the XRT and EIS data and wanted to cross-calibrate the DEMs -- but they look nothing like each other! So we can't yet use EIS and XRT to have large-T coverage DEMs that we believe.
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GAD: those limb-brightening curves about the limb: do you have O IV and O V? Cos that's a check on the scattered light?
HEM: they do fall off quite sharply
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PRY: For the AR, there was a paper last year that showed three separate isothermal components in the corona.
HEM: that's difficult for me to believe.
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Let's look at some CDS data taken above the limb, and it looks consistent with an isothermal plasma. Fairly well-established result. Now let's look with EIS. One of the things we found with SUMER is that the Si data seems to behave pretty well. Assume a delta-function EM and formalise the fit parameters. Get a pretty good fit. The density is being adjusted with intensity. The encouraging thing with EIS is that we get a similar result with the big strong lines that everyone includes in their studies. one thing that is unsettling is that the magnitude of the EM is different! This could mean Si / Fe ratio in the abundances of Feldman is wrong.
That's what can be done.
When you bring in Fe XIV - Fe XVI, they don't lie on the curves. So is there some dispersion in the temperature distribution? Then we end up with a fairly narrow distribution, but it doesn't account for the higher temperatures.
So another thing we've considered is MCMC used in PINTofALE. We also see a tail extending down to higher T. This accounts very well, but although tempting, it's not clear, because the ionisation fractions become very unclear as you get away from their peaks. Or maybe we really do have a tail in the DEM!
Ca XIV thru XVII help us to probe the high-T lines. Their contribution functions are narrower than the equivelant-T Fe species. Ca XIV and XV lines are fairly strong, and we should reconsider AR observations so that they include these lines.
GAD showed earlier an AR movie: I wanted to comment that the we show the Ko et al. deconvolution of Ca XVII.
As we move out from the core of the AR, we see the high-temperature emission coming down. Just because you dno't see any signal doesn't mean there's something wrong. Can still offer useful constraint for analysis. Something interesting is that the EM
Modelling evolving coronal loops with narrow-angle STEREO. Aschwanden has put a package on SSW for measuring loops' 3D geometry.
We're doing mutli-thread modelling of loops: we can calculate the expected lifetime of the loop, but it lasts much longer. We've put to gether such a multi-thread model. Good matches to TRACE loop lifetimes.
Another independent check is the DEM. Can approximate observed lifetime and DEM.
The way we motivate the heating in a loop, the higher the density, the more energy you've to put in.
We try to reproduce the XRT loops, and can't find those loops. May be that we can't find loops in XRT due to the morphology.
Would love to see the EIS slit over a post-flare loop arcade.
An important goal for the future. So, to summarise:
* QS above the limb
* AR DEMs
* Evolving loops.
HEM: I'm still confused by the isothermality... the heating models might predict a high-temperature tail.
HPW: There's no physical interpretation, that's what's so difficult to understand. Essentially indpendent of height. Maybe there is this hi-T component.
HEM: just not high-enough T lines?
HPW: We have Fe XV. There are always probs with atomic data, like Li-like lines...
KPD: One of the Fe XII lines could be being misidentified as Fe XI
HPW: It's hard to see how, because the ratio is extremely constant.
PRY: I remember fitting the lines, and the ratio was very flat.
GAD: Helen, you didn't get this isothermal plasma, but was it in an AR?
HPW: I thought it was in an AR?
Discussion continued....!
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Seems like almost everyone has spoken about outflows!
Seems a correlation between outflow speed and line widths. Can these widths be attributed to multiple components with different speeds? One such AR, we have observations as the AR rotates from east to west across the disc. The dominant outflow region seems to change position, but this could be a geometric effect.
Fit Fe XII 195, Fe XII 192, Fe XIII 202. Have used one of PRY's codes to fit a double Gaussian. Correlation between width and velocity remains, although it's not quite so clear for the smaller component at larger blue-shifts. These data are taken from each pixel in a box around the outflow region. Only done for the one active region, because the Gaussians were well separated.
LKH: does it change with time in the series of rasters you showed.
PB: not by much
KPD: The interesting thing is in the change of one flow region from redshifts to blueshifts.
In the core of the AR, the blend to the red side of the line becomes more important at higher densities.
GAD: how did you determine your zero velocity?
PB: Took a horizontal slice along the bottom
JTM: based on muliple simulations of loop flow problems, you have to be careful when fitting that if you choose two lumps of plasma: one moving and another static. I think Ken had the right idea when he used moments because you could use things like skew. that might be what this is telling you.
PB:
This page (revision-83) was last changed on 02-Feb-2017 13:19 by David R WilliamsTop