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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660773.0, MPI für Astronomie / Publikationen_mpia
WASP-4b transit observations with GROND
Authors:Nikolov, N.; Henning, T.; Koppenhoefer, J.; Lendl, M.; Maciejewski, G.; Greiner, J.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Astronomy and Astrophysics
Start Page:id.A159
Audience:Not Specified
Abstract / Description:Context. Ground-based simultaneous multiband transit observations allow an accurate system parameter determination and may lead to the detection and characterization of additional bodies via the transit timing variations (TTVs) method. <BR /> Aims: We aim to (i) characterize the heavily bloated WASP-4b hot Jupiter and its star by measuring system parameters and the dependence of the planetary radius as a function of four (Sloan g', r', i', z') wavelengths and (ii) search for TTVs. <BR /> Methods: We recorded 987 images during three complete transits with the GROND instrument, mounted on the MPG/ESO-2.2 m telescope at La Silla Observatory. Assuming a quadratic law for the stellar limb-darkening, we derived the system parameters by simultaneous fitting a composite transit light curve over all bandpasses. To compute uncertainties of the fitted parameters, we employed the bootstrap Monte Carlo method. <BR /> Results: The three central transit times are measured with precision down to 6 s. We find a planetary radius Rp = 1.413 ± 0.020 RJup, an orbital inclination i = 88.57 ° ± 0.45° and calculate a new ephemeris, a period P = 1.33823144 ± 0.00000032 days and a reference transit epoch T0 = 2 454 697.798311 ± 0.000046 (BJD). Analysis of the new transit mid-times in combination with previous measurements shows no sign of a TTV signal greater than 20 s. We perform simplified numerical simulations to place upper-mass limits of a hypothetical perturber in the WASP-4b system. Based on observations collected with the Gamma Ray burst Optical and Near-infrared Detector (GROND) at the MPG/ESO-2.2 m telescope at La Silla Observatory, Chile. Programme 083.A-9010.Light curves are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A159">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A159</A>
Free Keywords:planets and satellites: fundamental parameters; methods: data analysis; planetary systems
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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