| Abstract | High resolution H I observations are presented of the barred spiral galaxy NGC 3992 and three nearby satellite systems, and these data are used to estimate the galaxy's mass and mass distribution. An analysis of rotation velocities leads to a disk mass estimate of 200 billion solar masses within a 19.7 kpc radius. It is suggested that the motions of the galaxy's satellites, which may not allow a mass greater than about 400 billion solar masses within a mean radius of 59 kpc, could be overestimated by a factor of two. It is concluded that the mass of the system does not increase linearly with distance, and that the galaxy is not likely to possess a halo as massive as one trillion solar masses, leaving open the question posed by the galaxy's flat rotation curve. |
