Classical Novae--A Steady State, Constant Luminosity, Continuous Ejection Model

A model of classical novae is considered in which a steady outflow of matter occurs. It is suggested that this outflow is driven by radiation pressure in the continuum. Approximate photospheric relations. are derived for such a continuously outflowing region (in which scattering is assumed the dominant opacity source). Using these, six novae are shown to have outflow rates of $$\dot{m} \sim 10^{21} - 10^{22} \,\text{g s}^{-1}$$ at maximum light. Physical grounds for this mass-loss rate are given. The behaviour of nova DK Lac as determined by Larsson-Leander is shown to be compatible with a constant total luminosity during the decline phase (i.e. the observed magnitude–effective temperature relation during the decline is derived theoretically). This is in agreement with the ultraviolet observations of FH Ser by Gallagher & Code. It is shown that, if all novae are similar, the physical conditions in the outflowing photosphere are only dependent on the magnitude of the decline from maximum light in the optical. It is suggested that this accounts for the observed spectral type/decline stage correlation of classical novae. It is shown that the oscillations and irregular behaviour associated with the transition phase in the optical light curves occurs when the outflowing envelope has dimensions which are of the same order as the underlying binary separation.