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(Week 40, 2002, 30 Sept - 06 Oct.)
In the display above
(click to enlarge),
the solar X-ray fluence seen by RESIK
(black points) is plotted atop GOES red
line. Only periods with good spectral measurements are indicated.
The total number of good spectral measurements is given in the title line.
| Observing Mode: | Dynamic data gather interval (DGI) between 2 and 302 s depending on activity level. | |
| Calibration : | No Calibration made | |
| ADS Settings: | Amplitude Discriminator settings used: | |
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Missing data due to telemetry gaps:
total 2:17 h
Spectral Ranges Observed by RESIK
As an example the spectra recorded during the decay of the long lasting X1.5 class limb flare on April 21, 2002 (GOES flare maximum at 01:51 UT) are presented (http://www.cbk.pan.wroc.pl/publications/2002/Praga_paper.htm).
On the horizontal axis the spectral bin numbers are displayed. The main spectral lines are identified. The unique are RESIK observations of He-like K (K XVIII) ion triplet in #1. The resonance line (w) at the wavelength of 3.531 Å, intercombination lines (x, y) at 3.545 Å, 3.549 Å and forbidden line (z) at 3.570 Å are pronounced. Potassium has low coronal abundance (Ael = 8.9 · 10-8) and so the X-ray emission from its He-like stage in solar flares is expected to be very weak.
There do not appear to be any solar flare observations of these lines from previous instruments. However they have been observed from the laboratory laser-produced plasmas and reported by Feldman et al., 1974, ApJ. 192, 213. Although not marked in the presented spectrum the Lya line of Ar XVIII can be resolved at the position of ~175 bin number. In #2 the most prominent are the line emission due to He-like Ar (Ar XVII). As the coronal abundance of an argon is much higher in comparison with potassium (Ael = 3.802 · 10-6) the much more intense, well resolved triplet (w, x, y, z) can be seen around the bin 330. Numerous dielectronic satellites due to Li-like Ar occur in the vicinity of these lines most of which are weak and not distinguishable in RESIK spectra. An unidentified statistically significant feature around 425 bin is marked.
The K and Ar spectra are of particular interest in the continuing debate on whether coronal element abundances depart from photospheric element abundances by factors that depend on element first ionization potential (FIP). The potassium FIP is very low (4.34 eV) while an argon has a relatively large FIP (15.76 eV). Several other line features are observed by RESIK. Among them are in this same channel #2, lines due to 1s2 - 1s3p, 1s2 - 1s4p transitions of He-like S XV ion. RESIK channel #3 includes the Lya line of H-like ion S XVI ~ 670 bin number (4.730 Å). The triplet of S XV ion can be identified in #4 (~800 bin number). All these lines offer the possibility of temperature determination as these transitions have different excitation energies.
Report prepared by: Barbara Sylwester bs@cbk.pan.wroc.pl
The report presented has been done in "real time" and so it may
contain jargon, blunders, or trivialities. We do not have also an English
native speaker in our Wroclaw group! We would be happy to discuss problems
mentioned above in more details if necessary.
RESIK data are in the open public domain and can be requested from:
http://surfwww.mssl.ucl.ac.uk/surf/data_request.html
Page made by: Jarek Bakala jb@cbk.pan.wroc.pl
