Research Interests
Kinematics and Dynamics
Kinematics is the study of velocity measurements, it tells us how things are moving. The average velocity and the spread in velocities of an ensemble can tell us a lot about the ensemble and its enviroment. Dynamics connects the measurements to the underlying physics and tells us why things are moving the way they are. My research primarily uses kinematic data and dynamical models in order to investigate the properties, structure and formation history of galaxies and stellar clusters. The motions of stars in a stellar system are sensitive to the mass of the system and this gives us a way of detecting "hidden" mass that we cannot see with telescopes; by modelling the kinematics, we can determine how much mass is present and where that mass is located. I primarily use proper motion kinematics for my work and I am an expert an the analysis of large proper motion datasets.
Globular Clusters
Globular clusters present an interesting dynamical puzzle as they are collisional systems; despite the name, the stars don't actually collide, but they do interact (and share energy), which affects their motions. Disentangling the various effects can be challenging and requires very accurate kinematic measurements. Fortunately the exquisite astrometric precision of the Hubble Space Telescope and Gaia makes it possible to make such measurements.
Local Group Galaxies
Galaxies form via mergers and accretions, the signatures of which remain coherent in velocity data for far longer than they do in spatial data, which makes kinematic data a very important tool for determining the present structure of galaxies and unravelling their formation histories. I have a particular interest in the denizens of the Local Group.