LONG-PERIOD VARIABLES IN THE LARGE MAGELLANIC CLOUD .3. EVIDENCE OF A KINEMATIC SPHEROIDAL POPULATION

Radial velocities obtained for a sample of the LPVs discovered in the LMC by Hughes [AJ, 97, 1634 (1989)] and Reid et al. [MNRAS, 232, 53 (1988)] shows that the shorter period LPVs have a high velocity dispersion and low rotational velocity about the LMC, giving direct evidence that they are one of the oldest field populations yet studied in the LMC and that they belong to a flattened spheroid population. This is the first evidence of the LMC possessing a spheroidal population. A kinematic analysis applied to a wide range of LMC populations (H I gas, CO molecular clouds, planetary nebulae, clusters, and CH stars) shows that the dynamics of the LMC is dominated by a single rotating disk, that the transverse velocity of the LMC is approximately 200 km s-1, and that all major populations of the bar have solid-body rotation. The dispersion ages for the PN, clusters, CH stars, and intermediate-age LPVs are all similar at approximately 4 Gyr. The velocity distribution of the old LPVs indicates the mass of the LMC is less-than-or-similar-to 6.2 +/- 1.5 x 10(9) M . . The distribution of the population represented by the old LPVs is highly flattened, with an axial ratio approximately 0.3-0.5, and its mass is approximately 2% of the LMC's total mass.