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1.
Theoretical electron-temperature-sensitive Ne vii emission line ratios, calculated using accurate R-matrix electron impact excitation rates, are presented for R
1 = I(895.2 Å)/ I(465.2 Å), R
2 = I(561.7 Å)/ I(465.2 Å) and R
3 = I(564.5 Å)/ I(465.2 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals good agreement between theory and experiment. This provides observational support for the accuracy of the atomic physics adopted in the calculations, and the methods employed in the derivation of the theoretical diagnostics. 相似文献
2.
R-matrix calculations of electron impact excitation rates for transitions in Si iii are used to derive the electron-density-sensitive emission line ratios R
1 = I(1113.2 Å)/ I(1206.3 Å), R
2 = I(1298.9 Å)/ I(1206.3 Å), and R
3 = I(1296.7 Å)/ I(1206.3 Å). A comparison of these with observational data for several solar features obtained with the Harvard S-055 spectrometer on board Skylab reveals that theory and experiment are compatible if the electron temperature of the Si iii emitting region of the solar atmosphere is log T
e
= 4.5, but not if log T
e
= 4.7. The implication of the choice of a lower temperature on the electron energy distribution function is also briefly discussed. 相似文献
3.
Relative level populations in Oiii, determined using R-matrix calculations of electron impact excitation rates, are used to derive the theoretical emission line ratios R
1 = I(525.80 Å)/ I(599.62 Å), R
2 = I(507.41 Å)/ I(599.62 Å), R
3 = I(507.71 Å)/ I(599.62 Å), and R
4 = I(508.18 Å)/ I(599.62 Å). Electron temperatures deduced from the observed values of these ratios for several solar features obtained with the NRL S082A slitless spectrograph on board Skylab are in good agreement, and also compare favourably with that of maximum Oiii fractional abundance in ionisation equilibrium, log T
max = 4.96. These results provide experimental support for the accuracy of the atomic data adopted in the line ratio calculations. 相似文献
4.
Electron impact excitation rates for transitions in the S v ion, calculated with the R-matrix code, are used to derive the electron temperature sensitive emission line ratios R
1 = I(854.8 Å)/ I(786.9 Å), R
2 = I(852.2 Å)/ I(786.9 Å), R
3 = I(849.2 Å)/ I(786.9 Å), and R
4 = I(1199.1 Å)/ I(786.9 Å), which are found to be significantly different from previous estimates. A comparison of the present results with observational data for a sunspot obtained with the Harvard S-055 spectrometer on board Skylab reveals generally good agreement between theory and experiment, except in the case of R
1, which is probably due to blending in the 854.8 Å feature. The possible effects of Lyman continuum absorption on the observed line ratios is briefly discussed. 相似文献
5.
New theoretical electron temperature sensitive emission line ratios in Si iv involving the 3 d
2
D – 3 p
2
P and 4 s
2
S – 3 p
2
P multiplets at 1125 and 816 Å, respectively, are derived using recent R-matrix electron excitation rate calculations. A comparison of these with observational data for a solar active region at the limb obtained with the Harvard S-055 spectrometer on board Skylab reveals that there is good agreement between theory and observation for ratios that include the 2
D
3/2, 5/2 – 2
P
3/2 transition at 1128.3 Å. This is in contrast to the findings of Keenan, Dufton, and Kingston (1986) and provides support for the atomic data adopted in the calculations. However, the 2
D
3/2 – 2
P
1/2 line at 1122.5 Å appears to be severely blended, as suggested previously by Burton and Ridgeley (1970) and Feldman and Doschek (1977), as it leads to electron temperature estimates that differ significantly from that expected in ionisation equilibrium. The fact that the I(1122.5 Å)/ I(1128.3 Å) intensity ratios determined from several flare spectra are closer to theory than that for the active region indicates that the blending is probably due to species with relatively low ionization potentials, as noted by Flower and Nussbaumer (1975). Electron temperatures deduced for a sunspot are much lower than that predicted from ionisation balance calculations, in agreement with earlier results, and imply that a cooling flow may be present. 相似文献
6.
A comparison of Skylab S082A observations for several solar flares with calculations of the electron temperature sensitive emission line ratio R
1 = I(2 s2 p
1
P – 2 s
2
1
S)/ I(2 s2 p
3
P
1 - 2 s
2
1
S) = = I(256.68 Å)/ I(491.45 Å) in Be-like SXIII reveals good agreement between theory and experiment, which provides observational support for the accuracy of the adopted atomic data. However, observed values of the electron density sensitive ratio R
2 = I(2 s2 p
1
P – 2 s
2
1
S)/ I(2 p
2
3
P
2 - 2 s2 p
3
P
2) = = I(256.68 Å)/ I(308.96 Å) all lie below the theoretical high density limit, which is probably due to blending in the 308.96 Å line. 相似文献
7.
New R-matrix calculations of electron impact excitation rates in Caxv are used to derive theoretical electron density diagnostic emission line intensity ratios involving 2 s
22 p
2–2 s2 p
3 transitions, specifically R
1= I(208.70 Å)/ I(200.98 Å), R
2= I(181.91 Å)/ I(200.98 Å), and R
3= I(215.38 Å)/ I(200.98 Å), for a range of electron temperatures ( T
e=10 6.4–10 6.8 K) and densities ( N
e=10 9–10 13 cm –3) appropriate to solar coronal plasmas. Electron densities deduced from the observed values of R
1, R
2, and R
3 for several solar flares, measured from spectra obtained with the Naval Research Laboratory's S082A spectrograph on board Skylab, are found to be consistent. In addition, the derived electron densities are in excellent agreement with those determined from line ratios in Caxvi, which is formed at a similar electron temperature to Caxv. These results provide some experimental verification for the accuracy of the line ratio calculations, and hence the atomic data on which they are based. A set of eight theoretical Caxv line ratios involving 2 s
22 p
2–2 s2 p
3 transitions in the wavelength range 140–216 Å are also found to be in good agreement with those measured from spectra of the TEXT tokamak plasma, for which the electron temperature and density have been independently determined. This provides additional support for the accuracy of the theoretical line ratios and atomic data. 相似文献
8.
Using electron excitation rates calculated with the R-matrix code, theoretical Nixviii electron-temperature-sensitive emission line ratios are presented for R
1 = I(220.41 Å)/ I(320.56 Å) , R
2 = I(233.79 Å)/I(320.56 Å) , and R
3 = I(220.41 Å)/ I(292.00 Å) . A comparison of these with observational data for two solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab, reveals good agreement between theory and observation for R
1 and R
2 in two spectra, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, several of the measured ratios are much larger than theory predicts, which is probably due mainly to saturation of the strong 292.00 and 320.56 Å lines on the photographic film used to record the S082A data. A comparison of our line ratio calculations with active region observations made by the Solar EUV Rocket Telescope and Spectrograph (SERTS) indicate that a feature at 236.335 Å, identified as the Nixviii 3 p
2
P
3/2 - 3 d
2
D
3/2 transition in the SERTS data, is actually the Arxiii 2 s
22 p
2
3
P
0 - 2 s2 p
3
3
D
1 line. The potential usefulness of the Nixviii line ratios as electron temperature diagnostics for the solar corona is briefy discussed. 相似文献
9.
Theoretical Ar XIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurate R-matrix calculations, are presented for R
1 = I(242.22 )/ I(236.27 ), R
2 = I(210.46 )/ I(236.27 ), and R
3 = I(248.68 )/ I(236.27 ). Electron densities deduced from the observed values of R
1, R
2, and R
3 for solar flares obtained with the NRL S082A slitless spectrograph on board Skylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in Ca XV, which is formed at a similar electron temperature to that of Ar XIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios. 相似文献
10.
Theoretical Ca X electron temperature sensitive emission line ratios, derived using electron excitation rates interpolated from accurate R-matrix calculations, are presented for R
1 = I(419.74 )/ I(574.02 ,), R
2 = I(411.65 )/ I(574.02 ), R
3 = I(419.74 )/ I(557.75 ), and R
4 = I(411.65 )/ I(557.75 ). A comparison of these with observational data for three solar flares, obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab, reveals good agreement between theory and observation for R
1 and R
3 in one event, which provides limited support for the accuracy of the atomic data adopted in the analysis. However, in the other flares the observed values of R
1 – R
4 are much larger than the theoretical high-temperature limits, which is probably due to blending of the 419.74 line with C iv 419.71 , and 411.65 with possibly C iii 411.70 . 相似文献
11.
Recent R-matrix calculations of electron impact excitation rates in Fe xii are used to derive the theoretical emission line ratio R
1 = I(195.1 Å)/ I(1242 Å), which is potentially a useful electron density diagnostic for the solar inner corona ( r 1.05 61-01). These results are found to be significantly different from the earlier estimates of Withbroe and Raymond (1984), but are in good agreement with the observed values of R
1, for the quiet Sun and an active region. Adoption of the R-matrix atomic data for the 1242 Å line in the coronal iron abundance determination removes an existing discrepancy between results derived from the EUV transition and other iron lines in the solar XUV spectrum. The R-matrix calculations confirm the prediction of Withbroe and Raymond that the earlier discrepancies in R
1 and the iron abundance were due to the 1242 Å line excitation rates being underestimated by a factor of ~2. Withbroe and Raymond's paper is, therefore, an excellent example of how astronomical observations can be used to accurately predict atomic physics data. 相似文献
12.
Theoretical electron-density-sensitive C III emission line ratios are presented for R
1 = I(2 s2 p
3
P – 2 p
2
3
P)/ I(2 s2 p
1
P – 2 p
2
1
S) = I(1176 Å)/ I(1247 Å), R
2 = I(2 s2 p
3
P – 2 p
2
3
P)/ I(2 s
2
1
S – 2 s2 p
3
P
1) = I(1176 Å)/ I(1908 Å), and R
3 = I(2 s2 p
1
P – 2 p
2
1
S)/ I(2 s
2
1
S – 2 s2 p
3
P
1) = I(1247 Å)/ I(1908 Å). These are significantly different from those deduced previously, principally due to the adoption of improved electron impact excitation rates in the present analysis. Electron densities deduced from the present theoretical line ratios, in conjunction with observed values of R
1, R
2, and R
3 measured from solar spectra obtained by the Naval Research Laboratory's S082B instrument on board Skylab, are found to be generally compatible. In contrast, previous diagnostic calculations imply electron densities from R
1, R
2, and R
3 that differ by up to two orders of magnitude. These results provide observational support for the accuracy of the atomic physics adopted in the present calculations, and the methods employed in the derivation of the theoretical line ratios. 相似文献
13.
Theoretical electron-density-sensitive emission line ratios in B-like AI ix are presented for R = I(385.01 )/ I(392.42 ). A comparison of these with high spectral resolution solar flare data, obtained with the S082A slitless spectrograph on board Skylab, reveals agreement between theory and observation for those spectra that were observed during the later stages of the flares. These results provide experimental support for the accuracy of the line-ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar observations from the S-055 instrument on board Skylab. However, the agreement between theory and observation for a spectrum obtained during the early stages of a flare is very poor, which probably indicates that the 392.42 line is blended with a transition arising from a species formed at a very high electron temperature. 相似文献
14.
Theoretical electron-temperature-sensitive Mg ix emission line ratios are presented for R
I = I(443.96 )/ I(368.06 ), R
2 = I(439.17 )/ I(368.06 ), R
3 = I(443.37 )/ I(368.06 ), R
4 = I(441.22 )/ I(368.06 ), and R
5 = I(448.28 )/ I(368.06 ). A comparison of these with observational data for a solar active region, obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals excellent agreement between theory and observation for R
1 through R
4, with discrepancies that average only 9%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on board Skylab. However in the case of R
5, the theoretical and observed ratios differ by almost a factor of 2. This may be due to the measured intensity of the 448.28 line being seriously affected by instrumental effects, as it lies very close to the long wavelength edge of the SERTS spectral coverage (235.46–448.76 ). 相似文献
15.
Results are presented for several theoretical line ratios in Nev involving transitions between multiplets in the 2 s
22 p
2 and 2 s2 p
3 configurations. A comparison of these with solar data from the S082A and S-055 instruments on board Skylab reveals generally good agreement between theory and experiment, especially in the case of the high-resolution (S082A) observations. However the 2 s
22 p
2
1
D – 2 s2 p
3
1
P (365.6 Å) and 2 s
22 p
2
3P – 2 s2 p
3
3
S (359 Å) lines appear to be blended, possibly with transitions in Fex and Fe xi/Fe xiii, respectively. We note that the intensity ratio I(365.6 Å) /I(416.2 Å) should be a valuable calibration check for a high-resolution extreme ultraviolet instrument in the spectral range 360–420 Å. 相似文献
16.
The ionized gas in NGC 1313 was studied by spectrophotometric means. The radial behaviour of the I(H)/ I(6584), I(6717)/ I(6731), N(N ii)/ N(H ii), and N(N ii)/ N(S ii) ratios and the deduced electron densities are discussed. The abundance ratios N(N)/ N(H) and N(N)/ N(S) for the nucleus and two emission regions were also derived and compared with previous data. 相似文献
17.
The recent level population calculations for Ne v by Aggarwal are used to determine the theoretical emission line ratios R
1 = I( 2s2p
3
1D o - 2s 22p 2
1D e)/I(2s2p 3
3D
2
0
- 2s 22p 2
3P
1
e
) and R
2 = I( 2s2p
3
1D o-2s 22p 2
1D e)/ I( 2s2p
3
3D
3
0
-2s 22p 2
3P
2
e
). A comparison of these with observational data for a solar flare and erupting prominence obtained with the NRL XUV spectrograph on board Skylab reveals that R
1 and R
2 are in their predicted high density limits. Although the ratios cannot be used as density diagnostics for values of n
e typical of the solar transition region, it is shown that they are temperature sensitive and hence may be employed to determine the electron temperatures of Ne v line emitting regions. 相似文献
18.
New theoretical emission line ratios for the Be-sequence ions Mg ix and Si xi are presented. A comparison with observational data for two solar flares and an active region loop obtained with the Harvard EUV spectrometer and NRL XUV spectroheliograph aboard Skylab reveals that these plasmas are in ionization equilibrium at coronal temperatures. Unfortunately most of the density diagnostics are not particularly useful under solar plasma conditions, as they vary only slightly over the electron density range 10 8–10 13cm –3. However the Si xi ratio I( 3
P
e
2 - 3
P
o
2)/ I( 3
P
o
1 – 1
S
e
0) is density sensitive in the range 10 8 to 10 10cm –3, which is representative of electron densities found in solar active regions or small flares. 相似文献
19.
The EUV observations from the SMM satellite of two sunspots are presented here. These observations show the sunspots (a) to be regions of lower intensity than the surrounding plage, contrary to that found by previous authors, and (b) to have line intensities which vary little over a period of several hours. An upper limit to mass flows of 2km s -1 is derived, indicating a relatively simple energy balance for the chromosphere-corona transition zone with thermal conduction being balanced by radiative losses. Electron densities derived from N iv to C iv line ratios imply electron pressures (log N
eT e) of 15.0 to 15.3. 相似文献
20.
Recent R-matrix calculations of electron impact excitation rates in N-like Si VIII are used to derive theoretical emission line intensity ratios involving 2s
22p
3–2s2p
4 transitions in the 216–320 Å wavelength range. A comparison of these with an extensive dataset of solar active region, quiet-Sun, sub-flare and off-limb observations, obtained during rocket flights of the Solar EUV Research Telescope and Spectrograph (SERTS), indicates that the ratio R
1= I(216.94 Å)/I(319.84 Å) may provide a usable electron density diagnostic for coronal plasmas. The ratio involves two lines of comparable intensity, and varies by a factor of about 5 over the useful density range of 108–1011 cm?3. However R
2= I(276.85 Å)/I(319.84 Å) and R
3=I(277.05 Å)/I(319.84 Å) show very poor agreement between theory and observation, due to the severe blending of the 276.85 and 277.05 Å lines with Si VII and Mg VII transitions, respectively, making the ratios unsuitable as density diagnostics. The 314.35 Å feature of Si VIII also appears to be blended, with the other species contributing around 20% to the total line flux. 相似文献
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