Disk accretion onto a weak-field neutron star - Boundary layer/disk luminosity ratio

X-ray bursters are considered to be neutron stars with a weak magnetic field that are undergoing disk-type accretion. If the field is weak enough, the disk will reach to the neutron star surface; next to the surface, a narrow boundary layer will develop, girdling the star. Using available formulations for luminosity and for free particle motion, it is shown that the boundary layer at the neutron star surface will be substantially more X-ray luminous than the extended accretion disk itself, unless the star is spinning exceptionally fast.