Broadband Linear Polarization in the Region of the Open Star Cluster NGC
  1817
  Multi-band linear polarimetric observations of 125 stars in the region of the
cluster NGC 1817 have been carried out intending to study properties of
interstellar dust and grains in that direction. The polarization is found to be
wavelength-dependent, being maximum in the V band with an average value of
0.95%. The foreground interstellar dust grains appear to be the main source of
linear polarization of starlight toward the direction of NGC 1817. The average
value of the position angle in the V band of 119.2 degree is found to be less
than the direction of the Galactic parallel in the region, indicating that the
dust grains in the direction are probably not yet relaxed. Spatial distribution
of dust appears to be more diverse in the coronal region than the core region
of the cluster. The maximum value of the degree of polarization is estimated to
be 0.93% for members of the cluster using the Serkowski relation. The average
value of wavelength corresponding to the maximum polarization of 0.54+/-0.02
micron indicates that the size distribution of dust grains in the line of sight
is similar to that of the general interstellar medium. Several variable stars
in the cluster were also observed for polarimetrically and pulsating variables
appear to have a slightly lower value of polarization from other nonvariable
member stars of the cluster. There are indications of the existence of dust
layers existence in front of those clusters which are located close to galactic
plane while for clusters located away from galactic plane no major dust layers
are observed.
