Abstract

"The physical properties of the equatorial ""subcentral vicinity"" of quadrant IV of the Milky Way disk are investigated using a multi-line analysis of the observed ratios R13/12=13CO(J=1?0)/ 12CO(J=1?0) and R21/10=12CO(J=2?1)/ 12CO(J=1?0), and models with one and two components. Comparison with kinematical stability parameters reinforces our view of galactic structure and suggests a ""Smith Law"" like relationship for the massive star formation on galactic scales (i.e. kpc scale). © 2005: Instituto de Astronomía, UNAM."