A radiation transfer model for the Milky Way. II The global properties
  and large scale structure
  We obtained an axi-symmetric model for the large-scale distribution of stars
and dust in the Milky Way (MW) using a radiative transfer code that can account
for the existing near-infrared (NIR)/mid-infrared/submm all-sky emission maps
of our Galaxy. We find that the MW has a star-formation rate of ${
SFR}=1.25\pm0.2\,{ M}_{\odot}$/yr, a stellar mass $M_{*}=(4.9\pm
0.3)\times10^{10}\,{ M}_{\odot}$, and a specific SFR that is relatively
constant with radius (except for the inner 1 kpc). We identified an inner
radius $R_{ in}= 4.5$\,kpc beyond which the stellar emissivity and dust
distribution fall exponentially. For $R<R_{ in}$ the emissivities fall linearly
towards the centre. The old stellar populations in the disk have an exponential
scalelength that increases monotonically from $h_{ s}^{ disk}(K)=2.2\pm
0.6$\,kpc in the NIR, to $h_{ s}^{ disk}(B)=3.2\pm 0.9$\,kpc at the shorter
optical bands, and a scaleheight that varies with radial distance, from $z_{
s}^{ disk}(0)=140\pm 20$\,pc in the centre to $z_{ s}^{ disk}(R_{\odot})=300\pm
20$\,pc at the solar radius. The young stellar populations have a scalelength
of $h_{ s}^{ tdisk}=3.2\pm 0.9$\,kpc and a scaleheight that varies from $z_{
s}^{ tdisk}(0)=50\pm 10$\,pc in the centre to $z_{ s}^{ tdisk}(R_{\odot})=90\pm
10$\,pc at the solar radius. We discovered an inner stellar disk within the
central 4.5 kpc, which we associate with the extended long bar of the MW. Most
of the obscured star formation happens within this inner thin disk. The diffuse
dust is mainly distributed in a disk with scalelength $h_{ d}^{ disk}=5.2\pm
0.8$\,kpc and scaleheight $z_{ d}^{ disk}=0.14\pm 0.02$\,kpc. We give the first
derivation of the MW attenuation curve and present it as a functional fit to
the model data. We find the MW to lie in the Green Valley of the main sequence
relation for spiral galaxies.
