Evidence of a counterrotating core in the Large Magellanic Cloud

Abstract

Stellar radial velocity data in the central region of the Large Magellanic Cloud (LMC) are used to estimate its radial velocity curve along various position angles (P.A.'s), including the line of nodes (LON). The central part of the radial velocity profile, along the LON, shows a V-shaped profile—a clear indication of counterrotation. The counterrotating region and the secondary bar have similar location and P.A. The origin of the counterrotating core could be internal (a secondary bar) or external (accretion). To explain the observed velocity profile, we propose the existence of two disks in the inner LMC, with one counterrotating. This two-disk model is found to match the H I velocities as well. Two disks with different LONs and velocity profiles can create regions that are kinematically and spatially separated. Their predicted locations are found to match the observed locations where the H I clouds are found to have two velocities.