Models for the soft X-ray emission of post-outburst classical novae

We developed a hydrostatic and stationary white dwarf envelope model for the study of the post-outburst phases of classical novae and their soft X-ray emission. We considered several white dwarf masses and chemical compositions typical of classical novae. Our results show that the luminosity, maximum effective temperature, and envelope masses depend on the white dwarf mass and on the chemical composition. Envelope masses for which equilibrium solutions exist are pretty small (∼10 −7 −10 −6 M� ), thus leading to a short duration of the soft X-ray emitting phase of classical novae, in agreement with most observations. The models we present provide a useful tool for the determination of the white dwarf properties from observable parameters in the X-ray range.

[1]  J. Krautter,et al.  The detection of X-rays from Nova MUSCAE 1983 with the EXOSAT satellite , 1984 .

[2]  J. MacDonald.  CNO abundances and the strengths of nova outbursts and hydrogen flashes on accreting white dwarfs. , 1983 .

[3]  Peter Bodenheimer,et al.  Studies in Stellar Evolution. III. The Calculation of Model Envelopes. , 1965 .

[4]  D. Prialnik,et al.  An extended grid of multicycle nova evolution models , 1995 .

[5]  I. Iben.  Hot accreting white dwarfs in the quasi-static approximation , 1982 .

[6]  L. G. Henyey,et al.  Studies in Stellar Evolution. VIII. The Time Scale for the Diffusion of Energy in the Stellar Interior , 1969 .

[7]  James MacDonald,et al.  Thermal X-ray emission from classical novae in optical decline , 1991 .

[8]  Steven N. Shore,et al.  Nuclear Turnoff Times for ONeMg Novae Determined Using Ultraviolet Spectral Evolution , 2001 .

[9]  J. Truran,et al.  CNO abundances and hydrodynamic models of the nova outburst. II - 1.00 solar mass models with enhanced carbon and oxygen , 1974 .

[10]  Joachim Krautter,et al.  The nebular phase of Nova GQ Muscae 1983 - Evolution of the ionization of the optical spectrum , 1989 .

[11]  M. Orio,et al.  X-ray emission from classical and recurrent-novae observed with ROSAT , 2001 .

[12]  Margarita Hernanz.  Classical nova explosions , 2002 .

[13]  J. Truran,et al.  Composition Influence upon the Core Mass-Luminosity Relation and Possible Implications for the Extinction Timescales of Classical Novae , 1998 .

[14]  R. Gehrz,et al.  Nucleosynthesis in Classical Novae and Its Contribution to the Interstellar Medium , 1998 .

[15]  A. Altamore,et al.  A study of the expanding envelope of Nova V1974 Cyg 1992 based on IUE high resolution spectroscopy , 2004, astro-ph/0403288.

[16]  Achim Weiss,et al.  Stellar Structure and Evolution , 1990 .

[17]  James MacDonald,et al.  The decline and fall of classical novae , 1985 .

[18]  Enrique García-Berro,et al.  On the Evolution of Stars That Form Electron-degenerate Cores Processed by Carbon Burning. II. Isotope Abundances and Thermal Pulses in a 10 M sun Model with an ONe Core and Applications to Long-Period Variables, Classical Novae, and Accretion-induced Collapse , 1996 .

[19]  J. Truran,et al.  Evolutionary sequences for Nova V1974 Cygni using new nuclear reaction rates and opacities , 1998 .

[20]  A. Glasner,et al.  The luminosity-core mass relation: why and how , 1983 .

[21]  William H. Press,et al.  Numerical Recipes: FORTRAN , 1988 .

[22]  Alan H. Karp,et al.  A variable order Runge-Kutta method for initial value problems with rapidly varying right-hand sides , 1990, TOMS.

[23]  Alexander V. Tutukov,et al.  On the Evolution of Symbiotic Stars and Other Binaries with Accreting Degenerate Dwarfs , 1996 .

[24]  H. Horn,et al.  Convective white-dwarf envelope model grids for H-, He-, and C-rich compositions , 1976 .

[25]  B. Paczyński.  One-zone model for shell flashes on accreting compact stars , 1983 .

[26]  Forrest J. Rogers,et al.  Updated Opal Opacities , 1996 .

[27]  J. Krautter,et al.  The Early Ultraviolet Evolution of the ONeMg Nova V382 Velorum 1999 , 2003, astro-ph/0301415.

[28]  Steven N. Shore,et al.  The Ultraviolet and X-ray View of the Demise of Nova V1974 Cygni , 1996 .

[29]  T. Ake,et al.  The early ultraviolet spectral evolution of Nova Cygni 1992 , 1993 .

[30]  G. Sala,et al.  Envelope models for the supersoft X-ray emission of V1974 Cyg , 2005, astro-ph/0502092.

[31]  J. José,et al.  Nucleosynthesis in Classical Novae: CO versus ONe White Dwarfs , 1997, astro-ph/9709153.

[32]  Mariko Kato,et al.  Optically thick winds and nova outbursts , 1994 .

[33]  M. Fujimoto.  A Theory of Hydrogen Shell Flashes on Accreting White Dwarfs - Part Two - the Stable Shell Burning and the Recurrence Period of Shell Flashes , 1982 .

[34]  I. Iben,et al.  Model stars with degenerate dwarf cores and helium-burning shells: a stationary-burning approximation , 1989 .

[35]  W. S. Fitch.  The Triply Periodic White Dwarf HL TAU-76 , 1973 .