Implications of recent measurements of the Milky Way rotation for the orbit of the Large Magellanic Cloud

Abstract

We examine the implications of recent measurements of the Milky Way (MW) rotation for the trajectory of the Large Magellanic Cloud (LMC). The ~14 ± 6 per cent increase in the MW circular velocity relative to the International Astronomical Union (IAU) standard of 220 km s-1 changes the qualitative nature of the inferred LMC orbit. Instead of the LMC being gravitationally unbound, as has been suggested based on a recent measurement of its proper motion, we find that the past orbit of the LMC is naturally confined within the virial boundary of the MW. The orbit is not as tightly bound as in models derived before the LMC proper motion was measured. © 2008 The Authors. Journal compilation © 2008 RAS.