The kinematics and internal dynamics of planetary nebulae in the small Magellanic Cloud

Kinematical and dynamical data for 44 SMC planetary nebulae (PNs) are presented at a velocity resolution of 12 km/s. The PNs form an unstructured spheroidal population apparently associated with the Bar with centroid at alpha 00 h 49 m 39 s, delta -73 deg 30 min (1950) and with a mean radial velocity of -17 km/s. Their velocity dispersion implies a mass of 900 million solar masses within a radius of 3 kpc of the centroid. These PNs, which form a population of age greater than about 100 million years, appear to be loosely associated with the lower velocity component of the H I, suggesting that the high-velocity H I component is dynamically young. A remarkably good correlation between the expansion velocity and the excitation class is found, which may show that the mass of the white dwarf central star is the major variable influencing the expansion velocity of PNs.