Institute for Advanced Study Astrophysics Seminar

Note: This talk is orthogonal to the one he gave at the symposium "The Variable Universe: A Celebration of Bohdan Paczyski" held at Princeton University this September. So this new talk would be of interest even if people saw the symposium talk. Abstract: When microlensing planet searches were proposed, it was expected that only one physical parameter of the system could be accurately measured: the planet/star mass ratio. 15 years and 7 planet detections later, we have often been able to measure the planet mass, the distance and transverse velocity of the system, the planet-star projected separation, and even in some cases, orbital properties. The additional information is teased out of higher-order effects, often in the face of a bewildering proliferation of model degeneracies. I analyze the physical origin of these higer-order effects and the degeneracies they bring with them, and discuss how modelers are overcoming these obstacles to derive new types of information about extrasolar planets.