5 Component structure in the nebular lines

The data used in this investigation are of sufficiently high resolution to show component structure in many of the nebular lines of RR Tel. For example, the [OIII] $\lambda$4363Å line shows definite evidence of a two component structure in the nebular emission (see Fig.4). Schild & Schmid ([1996]) note that this may illustrate a combination of a high density component with a logarithmic electron density ($N_{\rm e}$ in cm^-3) of $\sim$8, along with a low density component (log $N_{\rm e}$$\sim$5.5), which we found to be blueshifted by $\sim$28kms^-1 with respect to the high density feature (see Fig.4), in comparison to the blueshift of $\sim$20kms^-1 found by Schild & Schmid.

  

Figure 4: The [OIII] 4363Å emission line profile, in RR Tel (flux measured in arbitrary units). The line profile has been fitted using two components, separated by $\sim$28kms-1, and indicated by dashed and dotted lines, while the solid line shows the approximate sum of these

  

Figure 5: The [OIII] line profiles at a) 4959Å and b) 5007Å, showing four-component structure; c) OII $\lambda$4072Å showing two component structure; d) three-component structure in NeIV $\lambda$4714Å (flux measured in arbitrary units)

The [OIII] lines at $\lambda\lambda$4959 and 5007Å also show component structure. However, in these cases, the line profiles comprise at least three components, making the modelling process much more complicated (see Fig.5). A detailed analysis of these lines may be used to demonstrate additional physical characteristics of the RR Tel system, such as its winds (Nussbaumer & Dumm [1997]). Similar structural attributes to those of the [OIII] lines may also be found in the profiles of OII, NII, NIII and NeIV. In the future we intend to pursue a detailed analysis of these and all the other nebular line profiles, in order to build up a comprehensive picture of the component structure of the RR Tel system.

We also find very strong component structure in the features at $\lambda\lambda$6825 and 7082Å. These are believed to be Raman-scattered OVI emission from the $\lambda\lambda$1032 and 1038Å resonance lines (Espey et al. [1995]; Schmid [1989]). The two components of both features are separated by $\sim$330kms^-1.