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  • 1
    Electronic Resource
    Electronic Resource
    Line intensity ratios of transitions within the 1s 22s 22p 2 ground configuration of Mgvii (1984)
    Springer
    Solar physics 94 (1984), S. 75-84 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using theR-matrix approach new calculations have been made for the electron impact excitation of the fine structure transitions within the 1s 22s 22p 2 ground configuration of Mgvii. The computations have been made at a large number of energies in order to account for the contribution of resonances. All partial waves withL ≤ 9 are included in the calculations which are considered to be sufficient for the convergence of collision strengths in the energy range below 65 Ry. From this collision strength data, excitation rate coefficients have been calculated at a series of electron temperatures which are employed in the computation of population of the five lowest levels of Mgvii. The line intensity ratios for the transitions3 P 1 →1 D 2 and3 P 2 →1 D 2 to3 P 1 →1 S 0 are then calculated in the temperature range of 105 to 107 K at electron densities in the range 106 to 1010 cm−3. The calculated values are in good agreement with the earlier available results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154808
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  • 2
    Electronic Resource
    Electronic Resource
    A comparison of theoretical line strengths for the 2s 22p 2 − 2s2p 3 transitions in Ne v with solar data (1989)
    Springer
    Solar physics 122 (1989), S. 1-6 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results are presented for several theoretical line ratios in Nev involving transitions between multiplets in the 2s 22p 2 and 2s2p 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 2s 22p 2 1 D − 2s2p 3 1 P (365.6 Å) and 2s 22p 2 3P − 2s2p 3 3 S (359 Å) lines appear to be blended, possibly with transitions in Fex and Fexi/Fexiii, 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162824
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of theoretical O iii line strengths with XUV solar observations from the S082A instrument on board Skylab (1989)
    Springer
    Solar physics 122 (1989), S. 7-12 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract 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, logT max = 4.96. These results provide experimental support for the accuracy of the atomic data adopted in the line ratio calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162825
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  • 4
    Electronic Resource
    Electronic Resource
    Emission line ratios for Fexxi applicable to the XUV spectra of solar flares (1994)
    Springer
    Solar physics 149 (1994), S. 129-135 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron impact excitation rates for Fexxi, calculated with theR-matrix code, are used to determine theoretical electron density sensitive emission line ratios involving transitions in the 121–146 Å wavelength range. The observed ratios for a solar flare, obtained with a grazing spectrometer on board the OSO-5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.3 dex. In addition, the derived values ofN e are similar to those estimated for the high temperature regions of other solar flares. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645183
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  • 5
    Electronic Resource
    Electronic Resource
    Ar XIII line ratios in solar flares (1993)
    Springer
    Solar physics 145 (1993), S. 291-296 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Theoretical ArXIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurateR-matrix calculations, are presented forR 1 =I(242.22 Å)/I(236.27 Å),R 2 =I(210.46 Å)/I(236.27 Å), andR 3 =I(248.68 Å)/I(236.27 Å). Electron densities deduced from the observed values ofR 1,R 2, andR 3 for solar flares obtained with the NRL S082A slitless spectrograph on boardSkylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in CaXV, which is formed at a similar electron temperature to that of ArXIII. 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690657
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  • 6
    Electronic Resource
    Electronic Resource
    Oscillator strengths for optically allowed transitions in carbon-like ions (1984)
    Springer
    Solar physics 90 (1984), S. 281-290 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using configuration interaction wavefunctions, the excitation thresholds for the twelve lowest terms arising from the configurations 1s 22s 22p 2, 1s 22s2p 3, and 1s 22p 4 of Mgvii have been calculated. The same wavefunctions have been used to calculate the oscillator strengths for the optically allowed transitions in Mgvii. Combining these results with earlier published values for Oiii, Nev, Siix, Caxv, and Fexxi, oscillator strengths for other ions in the carbon isoelectronic sequence (F through Ni) have been predicted. The predicted values are found to be slightly lower when compared with the available published results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173956
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  • 7
    Electronic Resource
    Electronic Resource
    Mg vii and Si ix line ratios in the sun (1986)
    Springer
    Solar physics 103 (1986), S. 225-230 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recent R-matrix calculations of electron excitation rates for Mg vii and Si ix are used to determine the theoretical density sensitive emission line ratios R 1= I(2s2p 3 1 D 0 - 2s 2 2p 2 1 D e )/I(2s2p 3 3 S 0 - 2s 2 2p 2 3 P 2 e ) and R 2= I(2s2p 3 1 P 0 - 2s 2 2p 2 1 D e )/I(2s2p 3 3 S 0 - 2s 2 2p 2 3 P 2 e ). These are found to be quite similar to the earlier results of Mason and Bhatia. Electron densities derived using observed R 1 and R 2 ratios from Skylab NRL XUV spectra of solar flares and active regions are in good agreement, and compare favourably with those deduced from ions formed at similar electron temperatures to Mg vii and Si ix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00147825
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  • 8
    Electronic Resource
    Electronic Resource
    Theoretical Ne v emission line ratios compared to solar observations (1986)
    Springer
    Solar physics 105 (1986), S. 47-50 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The recent level population calculations for Ne v by Aggarwal are used to determine the theoretical emission line ratios R 1 = I(2s2p 3 1Do - 2s22p2 1De)/I(2s2p3 3D 2 0 - 2s22p2 3P 1 e ) and R 2 = I(2s2p 3 1Do-2s22p2 1De)/I(2s2p 3 3D 3 0 -2s22p2 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156375
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  • 9
    Electronic Resource
    Electronic Resource
    Fe XXI emission line ratios as electron temperature diagnostics for the coronae of cool stars (1996)
    Springer
    Solar physics 169 (1996), S. 47-53 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Theoretical Fe xxi electron temperature and density sensitive emission line ratios are presented for $$R_1 = I\left( {2s^2 2p^2 {}^3P_1 - 2s2p^3 {}^5S} \right)/I\left( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } \right)$$ and $$R_2 = T\left( {2s^2 2p^2 {}^3P_1 - 2s2p^2 {}^1S} \right)/T\left( {2s^2 2p^2 {}^3P_0 - 2s^2 2p^2 {}^3P_1 } \right)$$ . A comparison of these with observational data for the 1973 December 17 solar flare, obtained by the Naval Research Laboratory's S082A and S082B spectrographs on board Skylab, reveals reasonably good agreement between theory and observation for R 1[= I(242.07 $$\mathop \Lambda \limits^c$$ )/I(1354.08 Å)], which provides some support for the accuracy of the atomic data adopted in the line ratio calculations. However, our results for R 2 indicate that the emission feature in flare spectra at 338.06 Å, previously identified as the Fexxi 2s 22p 2 3 p 1 − 2s 22p 2 1 S line, is not due to this species but may be the Ca v 3p 4 3 p 1 − 3p 33d 3 P 2 transition. The potential of using R 1 as an electron temperature diagnostic for the Fe xxi line emitting regions of cool star coronae, through a combination of Extreme Ultraviolet Explorer and Hubble Space Telescope observations, is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00153832
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  • 10
    Electronic Resource
    Electronic Resource
    Evaluation of turbulent fluxes over Maitri, Antarctica (1995)
    Springer
    Boundary layer meteorology 74 (1995), S. 195-208 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Turbulent fluxes have been evaluated for clear sunny days over the Indian Antarctic station, Maitri, using the basic meteorological data recorded at four levels of a 28 m tower. The data are supplemented with radiation data. The surface layer over Maitri remains thermally stratified during the hours of minimum solar insolation, the so-called nighttime period. The surface winds during this period are generally very strong resulting in high momentum fluxes. In particular, for high winds (〉12 m s−1), the temperature gradient is found to be less positive than for moderate winds (4 to 7 m s−1). Solar insolation provided the daytime heating necessary for the diurnal variation of atmospheric stability, and hence, for the turbulent fluxes. Thus, on clear days daytime conditions are marked by upward transport of heat with reduced momentum flux, while stable nighttime conditions are marked by a downward heat flux with increased momentum fluxes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00715717
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