Polarization, Polarizing Efficiency, and Grain alignment towards the
  direction of the cluster NGC 2345
  We have investigated the grain alignment and dust properties towards the
direction of the cluster NGC 2345 using the multi-band optical polarimetric
observations. For the majority of the stars, the observed polarization is found
to be due to the interstellar medium with average values of maximum
polarization and wavelength corresponding to it as 1.55% and 0.58 $\mu m$,
respectively. This reveals a similar size distribution of dust grains to that
in the general interstellar medium in the direction of NGC 2345. Alteration of
dust properties near the distance of 1.2 kpc towards the direction of NGC 2345
has been noticed. The dust grains located beyond this distance are found to be
aligned with the Galactic magnetic field, whereas a dispersion in orientation
of the dust grains lying in the foreground of this distance is found.
Polarizing efficiency of grains in this direction is found to be close to the
average efficiency for our Galaxy. The decreased grain size along with the
increased polarizing efficiency towards the core region of the cluster
indicates the local radiation field is higher within the cluster which is
responsible for the increased alignment efficiency of small grains. The
wavelength of maximum polarization (associated with the average size of aligned
grains) is also found to increase with extinction and reduces with the increase
in polarizing efficiency, which can be explained by the radiative torque
alignment mechanism.
