New parameters and transit timing studies for OGLE2-TR-L9 b^*

¹ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: Monika.Lendl@unige.ch
² Universitäts-Sternwarte München, Scheinerstr. 1, 81679 Munich, Germany
³ Institut für Astronomie, Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
⁴ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099, USA
⁵ Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290 Versoix, Switzerland
⁶ Max Planck Institute for Extraterrestrial Physics, Giessenbachstr., 85748 Garching, Germany

Received: 5 May 2010
Accepted: 22 June 2010

Abstract

Context. Repeated observations of exoplanet transits allow us to refine the planetary parameters and probe them for any time dependent variations. In particular deviations of the period from a strictly linear ephemeris, transit timing variations (TTVs), can indicate the presence of additional bodies in the planetary system.

Aims. Our goal was to reexamine the largely unstudied OGLE2-TR-L9 system with high cadence, multi-color photometry in order to refine the planetary parameters and probe the system for TTVs.

Methods. We observed five full transits of OGLE2-TR-L9 with the GROND instrument at the ESO/MPG 2.2 m telescope at La Silla Observatory. GROND is a multichannel imager that allowed us to gather simultaneous light curves in the g′, r′, i′, and z′ filters.

Results. From our analysis we find that the semi-major axis and the inclination differ from the previously published values. With the newly observed transits, we were able to refine the ephemeris to 2454492.80008(±0.00014) + 2.48553417(±6.4 × 10^-7)E. The newly derived parameters are a = 0.0418 ± 0.0015 AU, r_p = 1.67 ± 0.05 R_j, and inc = 82.47° ± 0.12, differing significantly in a and inc from the previously published values. Within our data, we find indications for TTVs.