6 Conclusion

We present a detailed calibrated line list of the optical spectrum of RR Tel, listing 811 lines with identifications, including 320 lines not listed by McKenna et al. ([1997]). It was also necessary to discard some of the lines listed in the McKenna et al. study and to re-identify others; this was made possible by the improved resolution of the present study.

In this study, we have further investigated the changes that are continually occurring in the emission spectrum of RR Tel. We have found that the tendency towards higher levels of ionisation has continued (see Table 1), as noted by Kenyon et al. ([1993]) and Allen ([1980]).

We have noted strong component structure in many of the nebular emission lines. This structure can involve 2 or more components and may be evidence of a combination of high (log $N_{\rm e}$$\sim$8) and low density (log $N_{\rm e}$$\sim$5.5) emitting zones in the plasma (Schild & Schmid [1996]).

TiO absorption bandheads were found in the near infrared and red regions of the spectrum, which indicate the presence of the late type star in the RR Tel system, as noted by Thackeray ([1977]). These features are prominent in mid M type stars (Kirkpatrick et al. [1991]). Figure 3 shows our identifications of these bands.

This optical line list compliments the earlier work of Zuccolo et al. ([1997]) who have presented a study of the changes in the ultraviolet spectrum of RR Tel between 1978 and 1993, using the International Ultraviolet Explorer (IUE) satellite.

Acknowledgements

FLC is grateful to the Department of Education for Northern Ireland for the award of a research studentship. FCM is grateful to PPARC for her postdoctoral funding. This work was supported by NATO travel grant CRG/930722 and the National Science Foundation through Grants Nos. AST 90-14133, AST 93-13991, and AST 94-16985 to the University of California, Los Angeles. We are grateful to Alan Fitzsimmons, QUB, for obtaining the observations presented in this paper. We are also especially grateful to the referee, Regina Schulte-Ladbeck, for her invaluable criticisms and suggestions. This research has made use of NASA's Astrophysics Data System Abstract Service.