DHC 30June2004 Notes on the non-LTE modeling of the helium-like neon The first figure, sigOri_NeIX_complexatm_density.jpg, shows the f-i-r features for five different values of density (sorry about the key, the highest density model is labelled twice). The key lists the density in g/cc, but they correspond to log(n_ion) = 14, 13, 12, 11, and 10 (top to bottom in the key; i.e. low density, n=10^10 is turquoise). You can see the f-line (13.7 A) get weaker as the density increases. Of course, for a hot star, we don't believe the density can be high enough to account for the low or even absent forbidden line. So, the second figure, sigOri_NeIX_complexatm_radiation.jpg, shows the effects of the photospheric radiation field on the line complex. Here, the density is fixed at a low value (n=10^11 cm^-3) and the radiation field is varied according to the geometrical dilution caused by putting the X-ray emitting plasma farther and farther from the photosphere. The red line represents a distance of 10 Rstar, the blue line 3 Rstar, and the pink line 1 Rstar (i.e. right at the photosphere). I'm still working on getting an upper limit to the f/i ratio from the data, but it looks like we're going to conclude that R/Rstar < 3 for the neon. The wavelength of ^3S - ^3P photoexcitation for Ne is 1263 A. I've modeled the photospheric flux as a 33000 K blackbody. Note that in both plots, the y-axis is logarithmic, and the models have been convolved to a resolution of 800.