Implications of Recent Measurements of the Milky Way Rotation for the Orbit of the Large Magellanic Cloud

Understand

We examine the implications of recent measurements of the Milky Way rotation for the trajectory of the Large Magellanic Cloud.

• The ~ 14+/-6% increase in the MW circular velocity relative to the IAU standard of 220 km/s changes the qualitative nature of the inferred LMC orbit.
• Instead of the LMC being gravitationally unbound, as has been implied 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, although still not as tightly bound as in previous estimates.