Preliminary results of the analysis of the loop imaged with SPIRIT in the Mg XII 8.42 Å line on 22 October 2001 (by Fabio Reale)

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HEADER:
From a preliminary analysis, the imaged loop may be a long loop with maximum temperature of about 4-5 MK.

PROCEDURE:
- From the Yohkoh/SXT full frame image I estimated that the half-length of the loop is L~1.4e10 cm

- I computed a set of 11 model loops as in Serio et al. (1981) with uniform heating, all with half-length L=1.4e10 cm and with temperature at the apex logarithmically spaced from T=3.e6 to T=3.e7

- From the ssw CHIANTI I extracted the emissivity in the Mg XII 8.42 Å line

- I computed the emission along the loop in the Mg XII line for all the computed loops

RESULT:
The plot shows the emission distribution along half of the loop for the model loops (the apex is the right extreme, the labels are the corresponding apex temperatures in MK).



COMMENT:
The SPIRIT Mg XII image (in Sasha's powerpoint presentation) shows about 80% of the loop visible in the SXT image. If we look at the plot, we realize that the Mg XII line emission has a cutoff at 80% of the length (from the apex) for the models at about 4-5 MK (the second and the third from the bottom). Therefore my conclusion is that SPIRIT is imaging a (long) loop at about 4-5 MK.

Further steps:
- Compute the loop emission in the SXT filter bands.

- Detailed comparison of the model emission with the SPIRIT and SXT data: to do this I need the calibrated SPIRIT data (the calibrated image).