On the Properties of the Galactic Dust Layer within 700 pc of the Sun
  We compare the spatial stellar color variations with our 3D model of the
spatial dust distribution to refine the properties of the dust layer in
Galactic solar neighborhoods. We use a complete sample of 93992 clump giants
with an admixture of branch giants from the Gaia DR2 catalogue in a spatial
cylinder with a radius of 700 pc around the Sun extending to |Z|=1800 pc.
Accurate data of these stars in the Gaia DR2 GRP and WISE W3 bands have allowed
the spatial GRP-W3 color variations to be used to calculate the model
parameters and two characteristics of the sample, the mode of the dereddened
color (GRP-W3)0 of the giant clump and the linear change of this mode with
coordinate |Z|. As a result, an improved version of the three-dimensional model
first proposed by Gontcharov (2009b) has been obtained. As in the previous
version, the model suggests two dust layers, along the Galactic equator and in
the Gould Belt, that intersect near the Sun at an angle of 18\pm2 degs. In
contrast to the previous version of the model with a midplane of the Gould Belt
dust layer in the form of a circle with the center at the Sun, in the new
version this midplane is an ellipse decentered relative to the Sun. A scale
height of 170\pm40 pc has been found for both dust layers. The modes of the
absolute magnitude MW3=-1.70\pm0.02 and the dereddened color
(GRP-W3)0=(1.43\pm0.01)-(0.020\pm0.007)|Z|, where Z is expressed in kpc, have
been calculated for the giant clump near the Sun. The dispersions of the
quantities under consideration have allowed the natural small-scale density
fluctuations of the dust medium relative to the mean reddening calculated from
the model to be characterized. These fluctuations make a major contribution to
the uncertainty in the reddening.
