This is given by eq. (7) and is proportional to the spacetime velocity field in the plane of the galaxy. There is a magnetogravitational field in the axis perpendicular to the galactic plane. Therefore fluid gravitation gves a perfectly self consistent explanation of all the major aspects of a whirlpool galaxy, including the hyperbolic spiral orbit of stars, the large mass at the centre, and the velocity curve. This is the result of ECE2 unified field theory, in this case gravitation unified with fluid dynamics.