CPS team member Sarah Blunt recently led a paper documenting orbitize!, an open-source software package for fitting the orbits of directly imaged planets.

One of the perks of directly imaging exoplanets is that we can directly watch them moving along their orbits. However, only the most widely-separated exoplanets can be seen over the glares of their primary stars. These wide separations translate to orbital periods that take decades or longer, so even though we directly observe exoplanet orbital motion, we only see a small amount of it. It takes specially-developed algorithms and techniques to pick out statistics and orbital dynamics from these short orbital arcs, but the science is worth the struggle! As an example, Brendan Bowler used orbitize! in a forthcoming publication that compares the eccentricities of brown dwarfs and giant planets. Despite the short arcs these planets traverse over human timescales, Brendan was able to make a convincing statistical argument that brown dwarfs and giant planets have different underlying eccentricity distributions, which implies that they formed differently.

orbitize! makes the algorithms that Brendan used publicly available, and comes with pedagogical tutorials to teach the direct imaging community how to do these analyses. Sarah released an orbit visualization along with the paper, which allows users to see how the values of orbital elements affect observed orbits (see below). Users can download and directly interact with the visualization at this link.

The orbitize! paper is available at this link. The package itself is available here.