Orbital alignment and star-spot properties in the WASP-52 planetary system

L. Mancini, J. Southworth, G. Raia, J. Tregloan-Reed, P. Mollière, V. Bozza, M. Bretton, I. Bruni, S. Ciceri, G. D'Ago, M. Dominik, T. C. Hinse, M. Hundertmark, U. G. Jørgensen, H. Korhonen, M. Rabus, S. Rahvar, D. Starkey, S. Calchi Novati, R. Figuera JaimesTh. Henning, D. Juncher, T. Haugbølle, N. Kains, A. Popovas, R. W. Schmidt, J. Skottfelt, C. Snodgrass, J. Surdej, O. Wertz

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)


We report 13 high-precision light curves of eight transits of the exoplanet WASP-52b, obtained by using four medium-class telescopes,through different filters, and adopting the defocussing technique. One transit was recorded simultaneously from two different observatories and another one from the same site but with two different instruments,including a multi-band camera. Anomalies were clearly detected in five light curves and modelled as star-spots occulted by the planet during the transit events. We fitted the clean light curves with the jktebop code,and those with the anomalies with the prism+gemc codes in order to simultaneously model the photometric parameters of the transits and the position, size and contrast of each star-spot. We used these new light curves and some from the literature to revise the physical properties of the WASP-52 system. Star-spots with similar characteristics were detected in four transits over a period of 43 days. In the hypothesis that we are dealing with the same stars-pot, periodically occulted by the transiting planet, we estimated the projected orbital obliquity of WASP-52b to be λ = 3.°8 ± 8.°4. We also determined the true orbital obliquity, ψ = 20° ± 50°, which is, although very uncertain, the first measurement of ψ purely from star-spot crossings. We finally assembled an optical transmission spectrum of the planet and searched for variations of its radius as a function of wavelength. Our analysis suggests a flat transmission spectrum within the experimental uncertainties.
Original languageEnglish
Pages (from-to)843-857
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date1 Dec 2016
Publication statusPublished - 11 Feb 2017


  • Techniques: photometric
  • Stars: fundamental parameters
  • Stars: individual: WASP-52
  • Planetary systems


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