Measuring the Sun's velocity using Gaia EDR3 observations of Stellar Streams

Understand

We measure the Sun's velocity with respect to the Galactic halo using Gaia Early Data Release 3 (EDR3) observations of stellar streams.

• Our method relies on the fact that, in low-mass streams, the proper motion of stars should be directed along the stream structure in a non-rotating rest frame of the Galaxy, but the observed deviation arises due to the Sun's own reflex motion.
• This principle allows us to implement a simple geometrical procedure, which we use to analyse 17 streams over a $\sim 3-30$ kpc range.
• Our constraint on the Sun's motion is independent of any Galactic potential model, and it is also uncorrelated with the Sun's galactocentric distance.