Candidate dust structures for starlight polarization
  Rotation damping and alignment are discussed as prerequisites for
polarization power. An expression is derived from first principles, for the
damping time of the rotation of a particle in a magnetic field, under the
Faraday braking torque, provided its electrical properties are known. This
makes it possible to describe mathematically, in great detail, the motion of
the particle and determine its ultimate state of motion, if a steady state is
possible at all. This work defines, first, the necessary condition for the
Faraday braking to be effective: a) the net electronic charge distribution
should not be uniform throughout; b) the number of vibration modes should
exceed a few tens. Resonance of rotation frequency with any of these modes is
not a requirement. For alignment to be possible, the ratio of gyroscopic and
conservative magnetic to non-conservative (retarding) magnetic torques must be
low. Either dia-, para- or ferro-magnetism can do, and a small susceptibility
is enough and even preferable. This opens up a wide spectrum of possible
candidates. A few examples are given.
