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High-precision photometry by telescope defocussing – VIII. WASP-22, WASP-41, WASP-42 and WASP-55

Southworth, John and Calchi Novati, S. (2016) High-precision photometry by telescope defocussing – VIII. WASP-22, WASP-41, WASP-42 and WASP-55. Monthly Notices of the Royal Astronomical Society, 457 (4). pp. 4205-4217. ISSN 0035-8711. doi:10.1093/mnras/stw279.

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We present 13 high-precision and four additional light curves of four bright southern-hemisphere transiting planetary systems: WASP-22, WASP-41, WASP-42 and WASP-55. In the cases of WASP-42 and WASP-55, these are the first follow-up observations since their discovery papers. We present refined measurements of the physical properties and orbital ephemerides of all four systems. No indications of transit timing variations were seen. All four planets have radii inflated above those expected from theoretical models of gas-giant planets; WASP-55 b is the most discrepant with a mass of 0.63 MJup and a radius of 1.34 RJup. WASP-41 shows brightness anomalies during transit due to the planet occulting spots on the stellar surface. Two anomalies observed 3.1 d apart are very likely due to the same spot. We measure its change in position and determine a rotation period for the host star of 18.6 ± 1.5 d, in good agreement with a published measurement from spot-induced brightness modulation, and a sky-projected orbital obliquity of λ = 6 ± 11°. We conclude with a compilation of obliquity measurements from spot-tracking analyses and a discussion of this technique in the study of the orbital configurations of hot Jupiters.

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Calchi Novati, S.0000-0002-7669-1069
Additional Information:© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 February 1. Received 2016 January 28; in original form 2015 December 16. This study is based on data collected by MiNDSTEp with the Danish 1.54 m telescope at the ESO La Silla Observatory. The operation of the Danish 1.54-m telescope is financed by a grant to UGJ from the Danish Council for Independent Research, Natural Sciences (FNU). The reduced light curves presented in this work will be made available at the CDS ( and at We thank Laetitia Delrez and Marion Neveu-VanMalle for providing published light curves of WASP-41. J So acknowledges financial support from the Leverhulme Trust in the form of a Philip Leverhulme Prize. JTR acknowledges financial support from ORAU (Oak Ridge Associated Universities) and NASA in the form of a NASA Post-Doctoral Programme (NPP) Fellowship. DFE is funded by the UK's Science and Technology Facilities Council. EU-S acknowledges the support of CONICYT QUIMAL 130004 project. Funding for the Stellar Astrophysics Centre in Aarhus is provided by The Danish National Research Foundation (grant agreement no. DNRF106). The research is supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement no. 267864). TCH acknowledges KASI research grants #2012-1-410-02, #2013-9-400-00, #2014-1-400-06 and #2015-1-850-04. NP acknowledges funding by the Gemini-Conicyt Fund, allocated to project no. 32120036. GD acknowledges Regione Campania for support from POR-FSE Campania 2014–2020. YD, AE, OW and J Su acknowledge support from the Communauté française de Belgique - Actions de recherche concertées - Académie Wallonie-Europe. The following internet-based resources were used in research for this paper: the ESO Digitized Sky Survey; the NASA Astrophysics Data System; the SIMBAD data base and VizieR catalogue access tool operated at CDS, Strasbourg, France; and the arχiv scientific paper preprint service operated by Cornell University.
Funding AgencyGrant Number
Danish Council for Independent Research-Natural Sciences (FNU)UNSPECIFIED
Leverhulme TrustUNSPECIFIED
Oak Ridge Associated Universities (ORAU)UNSPECIFIED
NASA Postdoctoral ProgramUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)130004
Danish National Research FoundationDNRF106
European Research Council (ERC)267864 ASTERISK
Korea Astronomy and Space Science Institute (KASI)2012-1-410-02
Korea Astronomy and Space Science Institute (KASI)2013-9-400-00
Korea Astronomy and Space Science Institute (KASI)2014-1-400-06
Korea Astronomy and Space Science Institute (KASI)2015-1-850-04
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)32120036
Regione CampaniaPOR-FSE Campania 2014–2020
Communauté française de Belgique - Actions de recherche concertées - Académie Wallonie-EuropeUNSPECIFIED
Subject Keywords:stars: fundamental parameters – stars: individual: WASP-22, WASP-41, WASP-42, WASP-55 – planetary systems
Issue or Number:4
Record Number:CaltechAUTHORS:20160502-075001335
Persistent URL:
Official Citation:John Southworth, J. Tregloan-Reed, M. I. Andersen, S. Calchi Novati, S. Ciceri, J. P. Colque, G. D'Ago, M. Dominik, D. F. Evans, S.-H. Gu, A. Herrera-Cordova, T. C. Hinse, U. G. Jørgensen, D. Juncher, M. Kuffmeier, L. Mancini, N. Peixinho, A. Popovas, M. Rabus, J. Skottfelt, R. Tronsgaard, E. Unda-Sanzana, X.-B. Wang, O. Wertz, K. A. Alsubai, J. M. Andersen, V. Bozza, D. M. Bramich, M. Burgdorf, Y. Damerdji, C. Diehl, A. Elyiv, R. Figuera Jaimes, T. Haugbølle, M. Hundertmark, N. Kains, E. Kerins, H. Korhonen, C. Liebig, M. Mathiasen, M. T. Penny, S. Rahvar, G. Scarpetta, R. W. Schmidt, C. Snodgrass, D. Starkey, J. Surdej, C. Vilela, C. von Essen, and Y. Wang High-precision photometry by telescope defocussing – VIII. WASP-22, WASP-41, WASP-42 and WASP-55 MNRAS (April 21, 2016) Vol. 457 4205-4217 doi:10.1093/mnras/stw279 first published online February 8, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66569
Deposited By: Ruth Sustaita
Deposited On:02 May 2016 16:17
Last Modified:10 Nov 2021 23:59

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