Abstract
A realistic, yet very simple and analytical model for the galactic mass distribution is presented, which improves upon a similar model proposed in Allen and Martos (1986). The new potential is completely analytical; the density can be obtained from it in closed form and it is positive everywhere. Extreme mathematical simplicity is retained, as well as a good representation of the observed values of both the rotation curve and the perpendicular force. The new model consists of a spherical central bulge and a disk, both of the Miyamoto-Nagai (1975) form, plus a massive, spherical, halo. The total mass of the model is 9.00x1011 solar masses. The model escape velocity for objects in the solar vicinity is 535.7 km s-1. The values obtained for the galactic rotation constants are A = 12.95 km s-1kpc-1 and B = -12.93 km s-1kpc-1; they are in good agreement with recent observational data. In contrast to other models for our galaxy, the proposed potential function is extremely simple, fully analytical, continuous, and with continuous derivatives everywhere. The suitability of this potential for efficient and accurate numerical orbit computations is demonstrated by recalculating the orbits of several nearby, high velocity stars.
