Internal dynamics of the Large Magellanic Cloud from Gaia DR2

Abstract

We use the proper motions (PM) of half a million red giant stars in the Large Magellanic Cloud measured by Gaia to construct a 2D kinematic map of mean PM and its dispersion across the galaxy, out to 7 kpc from its centre. We then explore a range of dynamical models and measure the rotation curve, mean azimuthal velocity, velocity dispersion profiles, and the orientation of the galaxy. We find that the circular velocity reaches ∼90 km s^-1 at 5 kpc, and that the velocity dispersion ranges from ∼30-40 km s^-1 in the galaxy centre to ∼15-20 km s^-1 at 7 kpc.