The old-nova GK Per (1901). III. Accretion disc models.

Abstract

The UV spectrum of the old-nova GK Per (1901) at quiescence greatly differs from those of the other observed old-novae. In spite of the presence of high excitation emission lines, the UV to visual continuum energy distribution is peaked at ≡3600 Å, whereas for most old-novae it steeply rises towards shorter wavelengths. The authors have constructed a grid of models of accretion discs around a magnetic white dwarf for two physically different cases. A modification of the standard disc model in which the inner edge of the disc does not reach the star fails to reproduce the observed X-ray to infrared energy distribution. A better fit is achieved with a disc model whose radial temperature distribution has been changed by the presence of magnetic field lines; an inner radius ≥1.2×10⁹ cm and a mass transfer rate of ≅2×10¹⁶ g s^-1 are derived.