When trying to fit Lyman line profiles to Gaussians, it can be observed that below Ly11 the profiles become non-Gaussian, and below Ly8 clear signs of self-absorption become visible. Therefore, only the wings of the profiles were fitted to a Gaussian. As an example, the fit of H I Ly6 on 08 Jul 2000 is shown (see below). The effect of self-absorption in the profile center can be measured by comparing the raw data to the fit.
The results for the other Lyman lines are as follows:
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line wave logT | effect of self-absorption / %
_____________________|____(04 Jul 2000)_____|____(08 Jul 2000)___
| |
H I Ly17 914 4.20 | (- 1.9) | (+ 2.7) low signal
H I Ly16 914 4.20 | (+ 0.1) | (- 1.5) low signal
H I Ly15 915 4.20 | (- 0.5) | (- 1.7) low signal
H I Ly12 917 4.20 | (+ 0.5) | (+ 1.5) low signal
H I Ly11 918 4.20 | - 0.6 | - 2.3
H I Ly10 919 4.20 | - 1.1 | - 0.1
H I Ly9 920 4.20 | - 2.5 | - 1.6
H I Ly8 923 4.20 | - 6.0 | - 6.2
H I Ly7 926 4.20 | - 5.6 | - 7.3
H I Ly6 930 4.20 | - 5.3 | -10.8
H I Ly5 937 4.20 | -17.1 | -21.9
H I Ly4 949 4.20 | -14.2 | -23.8
In the figures below, intensities and widths of the Lyman lines are shown vs. their number. Please note that the fitted intensities (as stated in the table of Results II) are corrected here by the self-absorption observed in the center of the profile.
As in many other lines, the prominence of 08 Jul 2000 shows a narrower line width also in the Lyman lines. The prominence of 04 Jul 2000 appears to have a higher intensity in the Lyman lines, but the prominence of 08 Jul 2000 tends to show a higher self-absorption.
IED, 13 Aug 2001