  We study the polarization produced by scattering from dust in a bow
shock-shaped region of enhanced density surrounding a stellar source, using the
Monte Carlo radiative transfer code SLIP. Bow shocks are structures formed by
the interaction of the winds of fast-moving stars with the interstellar medium.
Our previous study focused on the polarization produced in these structures by
electron scattering; we showed that polarization is highly dependent on
inclination angle and that multiple scattering changes the shape and degree of
polarization. In contrast to electron scattering, dust scattering is
wavelength-dependent, which changes the polarization behaviour. Here we explore
different dust particle sizes and compositions and generate polarized spectral
energy distributions for each case. We find that the polarization SED behaviour
depends on the dust composition and grain size. Including dust emission leads
to polarization changes with temperature at higher optical depth in ways that
are sensitive to the orientation of the bow shock. In various scenarios and
under certain assumptions, our simulations can constrain the optical depth and
dust properties of resolved and unresolved bow shock-shaped scattering
regions.Constraints on optical depth can provide estimates of local ISM density
for observed bow shocks. We also study the impact of dust grains filling the
region between the star and bow shock. We see that as the density of dust
between the star and bow shock increases, the resulting polarization is
suppressed for all the optical depth regimes.

Solar and Stellar Astrophysics