Magnetic blanketing in white dwarfs

The influence of a strong magnetic field on line blanketing in white dwarfs is studied using a modified version of the model atmosphere programme Atlas. The splitting of the hydrogen lines is incorporated into the programme using an accurate but simple solution for the intensity in the polarized radiative transfer equations. When line broadening is assumed unchanged, magnetic line blanketing removes about 10 per cent more flux at 50 or 100 MG than at zero field; when the line components in a magnetic field are assumed to be only Doppler broadened, total line blanketing is greatly reduced. The magnetic lineblanketed atmosphere is not sufficiently different from the zero-field atmosphere to greatly affect previous line models of magnetic white dwarfs, since in most cases magnetic broadening (broadening caused by field spread) is the most important determinant of the appearance of the spectrum in the optical region.