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

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1. Introduction

Does the outburst of a symbiotic nova always lead to a long lasting mass-loss via a fast stellar wind, or could it occur without appreciable mass-loss?

Symbiotic novae occur in binary systems. They are due to thermonuclear reactions close to the surface of a white dwarf when accretion from the wind of the red giant has led to a critical mass. Thermonuclear reactions on white dwarfs that lead to bloated atmospheres, and their possible connection to symbiotic novae have been studied on many occasions, e.g. Kenyon & Truran (1983), Kenyon & Webbink (1984), Sion & Starrfield (1986), Prialnik (1986), Livio et al. (1989), Kato & Hachisu (1989), Shara et al. (1993), Iben & Tutukov (1996). In their study on evolutionary sequences of nova outbursts Prialnik & Kovetz (1995) find that for conditions appropriate to symbiotic novae there may be cases where the outburst is accompanied by mass-loss, whereas in other cases the outburst simply leads to an extended atmosphere without appreciable mass-loss. However, there is as yet no satisfactory detailed explanation for the mechanism of mass-loss in these systems. It is therefore all the more urgent, that in order to test theoretical predictions, reliable observational evidence is collected about the presence or absence of mass-loss during outburst. Mass loss is also crucial within the debate whether symbiotic novae may be precursors of type Ia supernovae. This possibility has been advocated by Munari & Renzini (1992). For further contributions see Yungelson et al. (1995) or Iben & Tutukov (1996). The hypothesis strongly rests on the assumption that thermonuclear outbursts in symbiotic novae are not accompanied by significant mass-loss.

In this work we collect the observational information relevant to the mass-loss history of RR Tel. For the outbursting star Jordan et al. (1994) find for 1992 an effective radiative temperature of [FORMULA] K and [FORMULA]. Penston et al. (1983) list in its spectrum strong resonance lines of medium ionized atoms, in particular the N V [FORMULA] 1238.8, 1242.8 doublet. If this doublet has its origin in a stellar wind, we expect a P Cygni absorption in the underlying stellar continuum, as was found in AG Peg (Nussbaumer et al. 1995). The limited dynamical range of IUE (International Ultraviolet Explorer) did not allow to clearly observe P Cygni features in symbiotics, that has changed with HST (Hubble Space Telescope).

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© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998