Modeling the Optical and UV Nebular Spectra of Nova Cygni 1992

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Session 29 -- Novae and Supernovae
Display presentation, Tuesday, 9:30-6:30, Pauley Room

[29.02] Modeling the Optical and UV Nebular Spectra of Nova Cygni 1992

S.J. Austin, S. Starrfield (ASU), R.M. Wagner (OSU), S.N. Shore (GHRS/CSC), G. Sonneborn (GSFC)

Nova Cygni 1992 is the brightest nova, V$\approx$4.4, to appear since Nova V1500 Cygni 1975. Its brightness and slow decline, t$_2\approx$24 days, have allowed us to obtain optical and IUE ultraviolet data at frequent intervals. The spectral evolution of Nova Cygni 1992 has been similar to that of the ONeMg nova QU Vul 1984. The reddening and distance we obtained for Nova Cygni 1992 are E(B-V)=0.3$\pm$0.1, and 1.7$\pm$0.2 kpc. High resolution optical line profiles from September 1992 and January 1993 show components at -80, $\pm$250, $\pm$480, $\pm$860 km sec$^{-1}$ suggesting non-spherical but ordered density structure. We present solutions for the temperature, density and chemical abundances of the ejected material during several stages of the outburst using a radiative-equilibrium photoionization code, CLOUDY, and standard nebular diagnostics. The preliminary modeling shows O, Ne, and Mg enhanced above solar supporting the theory that neon novae are the result of thermonuclear runaways on ONeMg white dwarfs. We have also simulated the high resolution optical line profiles assuming axially symmetric density configurations.

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