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Astron. Astrophys. 323, 387-392 (1997)

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5. Conclusions

The outburst of RR Tel began in October 1944. The nova event led to an extended atmosphere with a radius of [FORMULA], but without noticeable mass-loss. The transition to the nebular phase began between May and August 1949. It led to a small and hot radiative core. It was accompanied by growing mass-loss. The corresponding wind had terminal velocities of [FORMULA] km/s in October 1949, increasing to [FORMULA] km/s in 1960. After 1960 the wind diminishes, and from 1978 onward there is no trace of mass-loss. By 1960 the outbursting star had reached [FORMULA] K. After 1960 it evolved at approximately constant effective temperature but decreasing luminosity. When in 1978 IUE began to take high resolution spectra, evidence for a fast and significant stellar wind had disappeared. The observations of HST in 1995 confirm that result.

From a combination of HST, HUT, and ORFEUS observations we see that from 930 Å to 1400 Å the observed, de-reddened continuum can be well fitted with a black-body emission of [FORMULA] K and [FORMULA], corresponding to a hot star with [FORMULA]. At wavelengths [FORMULA] the nebular emission increasingly dominates the continuum.

Jordan et al. (1994) attribute the X-ray flux of RR Tel in 1992 mainly to a stellar atmosphere of [FORMULA] K and [FORMULA]. In addition they postulate a hot low luminosity plasma ([FORMULA]) of several [FORMULA] K, which could be due to a mass-loss wind of [FORMULA] /yr and [FORMULA] km/s. That wind would be too low to be detected by our observations.- The relative C/N/O abundances found by Nussbaumer et al. (1988) are not nova-like, and they are consistent with little contamination of the nebula by nova-processed matter.

For AG Peg, the oldest still active symbiotic nova, Vogel & Nussbaumer (1994) find during a very active phase a mass-loss rate of [FORMULA]. If we generously credit RR Tel with a similar wind for the period of 1950 to 1960, we arrive at a total mass-loss of [FORMULA]. The lowest total accreted mass listed by Prialnik & Kovetz (1995) for candidates of symbiotic novae is [FORMULA]. Thus, RR Tel will probably retain most of its formerly accreted mass.

The key to an estimate of the total mass-loss of RR Tel lies in the spectra taken between 1949 and 1960. It would be of great value if they were re-analyzed. A mass-loss analysis would require the visual magnitude, and equivalent widths and profiles of He I and He II wind lines.

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998