THE O-IV AND S-IV INTERCOMBINATION LINES IN SOLAR AND STELLAR ULTRAVIOLET-SPECTRA

被引:34
作者
COOK, JW
KEENAN, FP
DUFTON, PL
KINGSTON, AE
PRADHAN, AK
ZHANG, HL
DOYLE, JG
HAYES, MA
机构
[1] QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND
[2] QUEENS UNIV BELFAST,DEPT APPL MATH & THEORET PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND
[3] OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210
[4] ARMAGH OBSERV,ARMAGH BT61 9DG,NORTH IRELAND
[5] DARESBURY LAB,WARRINGTON WA4 4AD,CHESHIRE,ENGLAND
关键词
ATOMIC DATA; ATOMIC PROCESSES; SUN; UV RADIATION; ULTRAVIOLET; STARS;
D O I
10.1086/175664
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
New calculations of O IV electron density diagnostic emission-line ratios involving the 1399.8, 1401.2, 1404.8, and 1407.4 Angstrom transitions are presented. A comparison of these calculations with observational data from a quiet solar region, a sunspot, and an active region obtained with the High Resolution Telescope and Spectrograph (HRTS), two flares observed with the SO82B spectrograph on board Skylab, and Hubble Space Telescope observations by the Goddard High Resolution Spectrograph (GHRS) of Capella, gives good results using the ratio R(1) = I(1407.4 Angstrom)/I(1401.2 Angstrom). However, the electron density obtained using the ratio R(2) = I(1407.4 Angstrom)/I(1404.8 Angstrom) is often an order of magnitude smaller. The O IV 1404.8 Angstrom line is blended with the S IV 1404.8 Angstrom line, and we investigate whether this ratio may still be used as a density diagnostic if the S IV 1406.1 Angstrom line intensity is used to correct for the presence of S IV 1404.8 Angstrom, using previous S IV calculations by Dufton et al. We still find systematic differences compared to density determinations from line ratios that do not involve the O IV 1404.8 Angstrom line, which we suggest are due to errors in earlier theoretical calculations of the S IV atomic data, and also possibly to previously unconsidered fluorescent pumping of the upper level of the S IV 1404.8 Angstrom transition.
引用
收藏
页码:936 / 942
页数:7
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