Документ взят из кэша поисковой машины. Адрес оригинального документа : http://star.arm.ac.uk/~ambn/abstract187.ps Дата изменения: Fri Aug 16 13:49:53 1996 Дата индексирования: Mon Oct 1 23:34:28 2012 Кодировка: Поисковые слова: ultraviolet

The O IV and S IV intercombination lines in solar
and spectra ultraviolet spectra
J.W. Cook, F.P. Keenan, P.L. Dufton, A.E. Kingston, A.K.
Pradhan, H.L. Zhang, J.D. Doyle M.A. Hayes
New calculations of O IV electron density diagnostic emission line ratios involv­
ing the 1399.8 љ A, 1401.2 љ A, 1404.2 љ A, 1407.4 љ A transitions are presented. A com­
parision 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 љ A)/I(1401.2 љ A). However, the electron density obtained using the
Ratio R 2 = I(1407.4 љ A)/(1404.8 љ A) is often an order of magnitude smaller. The
O IV 1404.8 љ A line is blended with the S IV 1404.8 љ A line, and we investigate
whether this ratio may still be used as a density diagnostic if the S IV 1406.1 љ A
line intensity is used to correct for the presence of S IV 1404.8 љ A, using previous
S IV calcualtions by Dufton et al. We still find systematic difference compared
to density determinations from line ratios that do not involve the O IV 1404.8
љ A 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 љ A transition.
Subject headingss: atomic data ­ Sun: spectra ­ ultraviolet: spectra ­ stars:
late­type
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