SIMBAD references

We present the azimuthally averaged radial distribution of 748 regions of OB star formation in the whole galactic disk, based on our previous CS(2-1) survey of UC H II regions. Embedded massive stars produce a total FIR luminosity of 1.39x10⁸L_☉ within the range 0.2≤R/R₀≤2 in galactocentric radius. We find 492 massive star forming regions within the solar circle, producing 81% of the total FIR luminosity. Separate analyses of the 349 sources in the I and II quadrant (north), and of the 399 sources in the III and IV quadrant (south), yield FIR luminosities (extrapolated to the complete galactic disk) of 1.17x10⁸L_☉ and of 1.60x10⁸L_☉, respectively. Massive star formation is distributed in a layer with its centroid Z₀(R) following that of molecular gas for all galactocentric radii, both north and south. Its thickness for R≤R₀ is ∼73pc (FWHM), 62% the thickness of the molecular gas disk. The FIR luminosity produced by massive stars has a well defined maximum at R=0.55R₀, with a gaussian FWHM of 0.28R₀- compared with 0.51R₀ for the H₂ surface density distribution. Toward the outer Galaxy, down from the maximum, the face-on FIR surface luminosity decays exponentially with a scale length of 0.21R₀, compared with 0.34R₀ for the H₂ surface density. Massive star formation per unit H₂ mass is maximum for R∼0.55R₀ in the southern Galaxy, with a FIR surface luminosity to H₂ surface density ratio of ∼0.41L_☉/M_☉, compared with ∼0.21L_☉/M_☉ at the same radius in the north, and with an average of ∼0.18L_☉/M_☉ for the whole galactic disk within the solar circle.