SIMBAD references

We consider a white dwarf model with differential rotation and magnetic field, assuming that (1) the symmetry axis of the toroidal magnetic field, the magnetic axis of the poloidal magnetic field, and the principal axis I₃ coincide permanently with each other (this common axis is called ``magnetic symmetry axis'') and (2) the model declines slightly from axisymmetry, i.e., its magnetic symmetry axis is inclined at a small angle χ relative to its spin axis (this angle is called ``obliquity angle'' or ``turnover angle''). The latter assumption turns on the ``magnetic dipole radiation mechanism'', which is fed by the rotational kinetic energy and causes emission of weak electromagnetic power since χ is assumed small; thus, the model suffers from secular angular momentum loss. This fact leads to a gradual decrease of the moment of inertia I₃₃ along the principal axis I₃ and, in turn, to a gradual increase of the moment of inertia I₁₁ along the principal axis I₁, since the toroidal field (tending to derive prolate configurations and thus to increase I₁₁) becomes gradually more competitive against the combined action of both rotation and poloidal field (tending to derive oblate configurations and thus to increase I₃₃). So, a ``dynamical asymmetry'' is established in the sense that, after a particular time, I<sub>11</sub> becomes greater than I<sub>33</sub>. However, a dynamically asymmetric model tends to turn over spontaneously and thus to become ``oblique rotator'' with its angular momentum remaining invariant. As a consequence, the turnover angle increases spontaneously up to 90° on a ``turnover timescale'', t<sub>TOV</sub>, since the rotational kinetic energy of the model decreases from a higher level when χ≃0° to a lower level when χ≃90°; at this level the model becomes ``perpendicular rotator'' and reaches the state of least energy consistent with its prescribed angular momentum and magnetic field. The excess rotational kinetic energy due to differential rotation is totally dissipated due to the action of turbulent viscosity in the convective regions of the model. Thus, in the ``turnover scenario'' the casting of the roles has mainly to do with rotation, poloidal field, toroidal field, and turbulent viscosity. In the present paper, we study in detail this scenario.