Journal Article

High-precision photometry by telescope defocusing – IV. Confirmation of the huge radius of WASP-17 b

John Southworth, T. C. Hinse, M. Dominik, X.-S. Fang, K. Harpsøe, U. G. Jørgensen, E. Kerins, C. Liebig, L. Mancini, J. Skottfelt, D. R. Anderson, B. Smalley, J. Tregloan-Reed, O. Wertz, K. A. Alsubai, V. Bozza, S. Calchi Novati, S. Dreizler, S.-H. Gu, M. Hundertmark, J. Jessen-Hansen, N. Kains, H. Kjeldsen, M. N. Lund, M. Lundkvist, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, C. Snodgrass and J. Surdej

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 426, issue 2, pages 1338-1348
Published in print October 2012 | ISSN: 0035-8711
Published online October 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21781.x
High-precision photometry by telescope defocusing – IV. Confirmation of the huge radius of WASP-17 b

More Like This

Show all results sharing this subject:

  • Astronomy and Astrophysics

GO

Show Summary Details

Preview

We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5 mmag per point. Our revised orbital period is 4.0 ± 0.6 s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, Rb = 1.932 ± 0.052 ± 0.010 RJup (statistical and systematic errors, respectively), provides confirmation that WASP-17 b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6 RJup are found around comparatively hot (Teff > 5900 K) and massive (MA > 1.15 M) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up.

Keywords: stars: fundamental parameters; stars: individual: WASP-17; planetary systems

Journal Article.  7241 words.  Illustrated.

Subjects: Astronomy and Astrophysics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.