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Planet 30

Systematic analysis of stellar transit light curves for the characterization of short-period extrasolar planets

Principal Investigators

  • Dr. M. Pätzold
    Rheinisches Institut für Umweltforschung an der Universität zu Köln, Köln


More than 3500 extrasolar planets were discovered to date. The study of a large ensemble of planetary systems of different kind may allow to conclude on the formation and evolution of planetary systems and the associated physical processes. The transit method is the most successful method for the discovery of exoplanets. Space telescopes like CoRoT, Kepler and K2 observed a large number of stars simultaneously and continuously. The orbital period; the planetary radius and the planetary semi major axis relative to the radius of the star, the inclination and eccentricity of the planetary orbit are determined from the transit by fitting analytic light curve models. The planetary mass is determined from a combination of transit and ground-based radial velocity measurements (RV) or in some cases by transit time variation (TTV). Other physical properties of planetary systems were occasionally discovered in light curves (e.g. light reflected by planets, ellipsoid variation, differential rotation of the star, angle between the stellar rotation axis and the planetary orbit, eccentricity of planetary orbits). Only crude estimates exist for other properties (e.g., apsidal precession, moons, rings, and trojans). This project shall systematically examine all existing light curves with planetary transits from the Kepler, CoRoT and K2 missions for known and/or theoretically predicted variations before, during and after the transit. The large ensemble of light curves may also build the foundation for a statistical analysis which shall characterize previously unexplained variations in the light curves which may then describe the associated physical phenomena.We want to apply our extensive experience gained from the analysis of stellar light curves and planetary transits made on the space missions CoRoT, Kepler and K2. The data already processed with our detection pipeline shall be exploited in more detail. A new numerical light curve model shall be developed. This numerical model shall be able to simulate light curve phenomena not considered in the commonly used Mandel-Agol model. The model shall give estimates if certain phenomena are detectable in the light curves with today’s technique and which kind of stars may be suitable for observation (period, spectral type of star, etc.). The model shall help to clarify the physical reason of unknown phenomena. The systematic investigation of the light curves should increase the information and the number of parameters obtained directly from the light curve. In addition, the information shall be used to identify false positives.


Sascha Grziwa

Invited Guests

William D. Cochran

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