Doyle, J.G. and Summers, H.P. and Bryans, P. (2005) The effect of metastable level populations on the ionization fraction of Li-like ions. Astronomy and Astrophysics, 430 (2). L29-L32. ISSN 0004-6361Full text not available in this repository. (Request a copy from the Strathclyde author)
Lines from Li-like ions have been known to produce theoretical intensities under-estimated compared to lines of a similar formation temperature. Here we investigate this anomalous behaviour whereby the ionization fractions are calculated using the ADAS code considering the electron density dependence of dielectronic recombination coupled with collisional ionization from metastable levels. For the lines investigated, the line contribution functions show a clear dependence with increasing electron density. For example, C IV 1548 Angstrom shows over a factor of three enhancement for N-e = 10(12) cm(-3). The increase in the higher temperature lines is lower, but are still in the range of 30 to 60 Furthermore, all the lines have their peak contribution shifted to lower temperature. Calculating the total radiative power output at an electron density of 10(11) cm(-3), we find that the difference in the transition region is 10 - 15% while above 10(6) K the difference is around 30% compared to the low density value.
|Keywords:||atmosphere , di-electronic recombination , metastable levels , electron density , line intensity , UV/EUV radiation , Physics, Astronomy and Astrophysics, Space and Planetary Science|
|Subjects:||Science > Physics|
|Department:||Faculty of Science > Physics|
|Depositing user:||Pure Administrator|
|Date Deposited:||13 Jul 2011 08:56|
|Last modified:||27 Apr 2016 16:48|