Caustic Structures and Detectability of Circumbinary Planets in Microlensing

Understand

Recent discoveries of circumbinary planets in Kepler data show that there is a viable channel of planet formation around binary main sequence stars.

• Motivated by these discoveries, we have investigated the caustic structures and detectability of circumbinary planets in microlensing events.
• We have produced a suite of animations of caustics as a function of the projected separation and angle of the binary host to efficiently explore caustic structures over the entire circumbinary parameter space.
• Aided by these animations, we have derived a semi-empirical analytic expression for the location of planetary caustics, which are displaced in circumbinary lenses relative to those of planets with a single host.