Integral from -r0 to +r0 of (r0^2-r^2)/(R0-r)^2 dr r0 is radius of star. R0 is distance to star center from a satellite of the star.
The integral is most often approxiamted with something proportional to 1/R0² which is the case when r0 -> 0. I think the approximation is too course for modern precision demands. David David Jonsson, Sweden, phone callto:+46703000370
