Astrometry

Knowing where a star is — and how it moves — is as fundamental as knowing what it's made of. The Gaia mission has transformed this, delivering precise positions, parallaxes, and proper motions for over a billion stars and reshaping nearly every area of stellar and Galactic astronomy in the process.

I'm interested in what we can extract from astrometry when it's combined with spectroscopy and photometry. Distances and motions turn a catalogue of stars into a dynamical map of the Galaxy; subtle astrometric wobbles reveal unseen companions, from binary stars to black holes; and the careful treatment of astrometric uncertainties and selection effects is essential to doing any of this honestly.

Some directions:

• How do we combine astrometry with spectroscopy to get full phase-space and chemical information for stars?
• What can astrometric signals tell us about unseen companions and binarity?
• How do we account for the selection function of astrometric surveys when inferring population-level properties?

This theme ties closely to my work on population inference, where modelling the selection function correctly is everything.