2022MNRAS.509.2339N

We obtained an axisymmetric 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±0.2 M_☉ yr^–1, a stellar mass M_*=(4.9±0.3)×10¹⁰ M_☉, 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 disc have an exponential scale length that increases monotonically from h_s^disc(K)=2.2±0.6 kpc in the NIR, to h_s^disc(B)=3.2±0.9 kpc at the shorter optical bands, and a scale height that varies with radial distance, from z_s^disc(0) =140±20 pc in the centre to z_s^disc(R_☉) =300±20 pc at the solar radius. The young stellar populations have a scale length of h_s^tdisc=3.2±0.9 kpc and a scale height that varies from z_s^tdisc(0)=50±10 pc in the centre to z_s^tdisc(R_☉)=90±10 pc at the solar radius. We discovered an inner stellar disc 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 disc. The diffuse dust is mainly distributed in a disc with scale length h_d^disc=5.2±0.8 kpc and scale height z_d^disc=0.14±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.