3D Grid-Based Monte Carlo Code for Radiative Transfer through Raman and
  Rayleigh Scattering with Atomic Hydrogen -- STaRS
  Emission features formed through Raman scattering with atomic hydrogen
provide unique and crucial information to probe the distribution and kinematics
of a thick neutral region illuminated by a strong far UV emission source. We
introduce a new 3 dimensional Monte-Carlo code in order to describe the
radiative transfer of line photons that are subject to Raman and Rayleigh
scattering with atomic hydrogen. In this code entitled "${\bf S}$ejong
Radiative ${\bf T}$r${\bf a}$nsfer through ${\bf R}$aman and Rayleigh ${\bf
S}$cattering (${\it STaRS}$), each photon is traced until escape with a tag
attached carrying information including the position, direction, wavelength,
and polarization. The thick neutral scattering region is divided into numerous
cells with each cell being characterized by its velocity and density, which
ensures huge flexibility of the code in analyzing Raman-scattered features
formed in a neutral region with complicated kinematics and density
distribution. As a test of the code, we revisit the formation of Balmer wings
through Raman scattering of far UV continuum near Ly$\beta$ and Ly$\gamma$ in a
static neutral region. An additional check is made to investigate Raman
scattering of O VI in an expanding neutral medium. We find fairly good
agreement of our results with previous works, demonstrating the capability of
dealing with radiative transfer modeling that can be applied to
spectropolarimetric imaging observations of various objects including symbiotic
stars, young planetary nebulae, and active galactic nuclei.
