Transit Timing Variations Analysis in Exoplanet Host-Stars

R. PETRUCCI, P. MAUAS, E. JOFRÉ, ..., M. GOMEZ

Moscow - Moscú

Workshop; COSPAR 2014: 40th Scientific Assembly of the Committee on Space Research; 2014

Moscow State University

In a system composed only by a star and a transiting planet, it should be expected that the interval between successive minima be constant. However, if there is a third body in the system, periodic variations of this interval are expected. Therefore, it should be possible to detect other planetary-mass bodies around stars with an already known transiting planet. The less massive the perturber, the smaller the amplitudes of the timing variations, and the higher precision minimum central times (with errors of around seconds) are required. In this work we present a complete and homogeneous study of TTVs of WASP-4b and WASP-28b, carried out with argentinian telescopes (the Horacio Ghielmetti (THG) telescope, located at Cerro Bureck in the Complejo Astronómico El Leoncit, San Juan, and the 1.54 m telescope at Estación Astrofísica de Bosque Alegre, Córdoba. For WASP-4b we found that the O-C are not well fitted by a linear ephemeris. Considering that WASP-4 presents stellar activity, the variations in the mid-transit times might be explained by the presence of spots over the stellar surface during the transit. For WASP-28b we found that the O-C are well fitted by a linear ephemeris, with the exception of several outliers, which correspond to incomplete transits and very noisy observations. Therefore, we found no evidence of the presence of other bodies in any of the studied systems.