A Simplified Photodynamical Model for Planetary Mass Determination in Low-eccentricity Multitransiting Systems

Abstract Inferring planetary parameters from transit timing variations (TTVs) is challenging for small exoplanets because their transits may be so weak that determination of individual difficult or impossible. We implement a useful combination tools together provide numerically fast global photodynamical model. This used to fit the TTV-bearing light curve, in order constrain masses transiting low-eccentricity, multiplanet systems—and planets particular. present inferred dynamical and orbital eccentricities four multi-planet systems Kepler's complete long-cadence data set. test our model against Kepler-36/KOI-277, system with some most precisely determined through TTV inversion methods, find 5.56 +0.41 −0.45 9.76 +0.79 −0.89 Kepler-36 b c, respectively—consistent literature both value error. then improve mass Kepler-79/KOI-152, where values were physically problematic 12.5 +4.5 −3.6 , 9.5 +2.3 −2.1 11.3 +2.2 −2.2 6.3 +1.0 −1.0 Kepler-79 b, d, e, respectively. new constraints none existed before two systems. These are +3.2 −2.6 Kepler-450 3.3 +1.7 17.4 +7.1 −3.8 Kepler-595 c (previously KOI-547.03) The code here, called PyDynamicaLC made publicly available.