This article summarizes recent work on the luminosity and mass distribution of the Galactic bulge and disk , and on the mass of the Milky Way ’ s dark halo .
A new luminosity model consistent with the COBE NIR data and the apparent magnitude distributions of bulge clump giant stars has bulge/bar length of \simeq 3.5 { kpc } , axis ratios of 1 : ( 0.3-0.4 ) :0.3 , and short disk scale-length ( \simeq 2.1 { kpc } ) .
Gas-dynamical flows in the potential of this model with constant M/L fit the terminal velocities in 10 ^ { \circ } \leq|l| \leq 50 ^ { \circ } very well .
The luminous mass distribution with this M/L is consistent with the surface density of known matter near the Sun , but still underpredicts the microlensing optical depth towards the bulge .
Together , these facts argue strongly for a massive , near-maximal disk in our \sim L ^ { \ast } , Sbc spiral Galaxy .
While the outer rotation curve and global mass distribution are not as readily measured as in similar spiral galaxies , the dark halo mass estimated from satellite velocities is consistent with a flat rotation curve continuing on from the luminous mass distribution .