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Astron. Astrophys. 326, 629-631 (1997)

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4. Discussion

The component stars of most classical novae are K - M dwarfs orbiting white dwarfs. Warner (1995, Eq. 9.54) uses the calculations of Prialnik (1986) to find that [FORMULA] where [FORMULA] is the effective temperature and t is the time in years since eruption. This applies to a nova with a 1.25- [FORMULA] white dwarf, and novae with massive white dwarfs should have much higher discovery probabilities (Ritter et al. 1990). The white dwarf in a 300-year-old nova should therefore have [FORMULA]  K. White dwarfs this hot are observed to have [FORMULA] (Wesemael, Green, & Liebert 1985) and [FORMULA] (Sion & Liebert 1977). In B and [FORMULA] therefore, any white dwarf present should have absolute magnitudes comparable to or brighter than those of M0 or K7 dwarfs, with [FORMULA] and 9.55 and [FORMULA] and 8.23 (Bessell 1991), respectively. We see no obvious sign of a hot white dwarf in our red or blue spectra, however, nor of an accretion disk: if either Candidate 5a or 5b is the hibernating nova, it is in very deep hibernation indeed. Alternatively, these could just be M0 and K7 stars, and the nova has not yet been recovered. These stars' H [FORMULA] equivalent widths seem high for M0 or K7 dwarfs, which more typically are near 2 Å (Linsky et al. 1982). However, T Tauri stars abound in Orion, and H [FORMULA] emission from their accretion disks has equivalent widths ranging from [FORMULA] to [FORMULA]  Å (Jaschek & Jaschek 1987). Radial velocity studies could demonstrate whether either Candidates 5a or 5b are close binary stars. Until then, however, or until a more convincing candidate has been found, this novaif indeed it was a novashould be considered unrecovered.

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© European Southern Observatory (ESO) 1997

Online publication: October 15, 1997
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