EDP Sciences
Free access
Issue A&A
Volume 496, Number 1, March II 2009
Page(s) 259 - 267
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:200810929
Published online 14 January 2009

A&A 496, 259-267 (2009)
DOI: 10.1051/0004-6361:200810929

Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b

M. Gillon1, B. Smalley2, L. Hebb3, D. R. Anderson2, A. H. M. J. Triaud1, C. Hellier2, P. F. L. Maxted2, D. Queloz1, and D. M. Wilson2

1  Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
    e-mail: michael.gillon@obs.unige.ch
2  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
3  School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK

Received 7 September 2008 / Accepted 9 December 2008

Abstract
The gaseous giant planets WASP-4b and WASP-5b are transiting 12-magnitude solar-type stars in the Southern hemisphere. The aim of the present work is to refine the parameters of these systems using high cadence VLT/FORS2 z-band transit photometry and high-resolution VLT/UVES spectroscopy. For WASP-4, the new estimates for the planet radius and mass from a combined analysis of our VLT data with previously published transit photometry and radial velocities are $R_{\rm p} = 1.30^{+0.05}_{-0.04}$ RJ and $M_{\rm p} = 1.21^{+0.13}_{-0.08}$ MJ, resulting in a density $\rho_{\rm p} = 0.55^{+0.04}_{-0.02}$ $\rho_J$. The radius and mass for the host star are $R_\ast = 0.87^{+0.04}_{-0.03}$ $R_\odot$ and $M_\ast = 0.85^{+0.11}_{-0.07}$ $M_\odot$. Our ground-based photometry reaches 550 ppm at time sampling of ~50 s. Nevertheless, we also report the presence of an instrumental effect on the VLT that degraded our photometry for the WASP-5 observations. This effect could be a major problem for similar programs. Our new estimates for the parameters of the WASP-5 system are $R_{\rm p} = 1.09$ $\pm$ 0.07 RJ, $M_{\rm p} = 1.58^{+0.13}_{-0.10}$ MJ, $\rho_{\rm p} = 1.23 ^{+0.26}_{-0.16}$ $\rho_J$, $R_\ast = 1.03^{+0.06}_{-0.07}$ $R_\odot$, and $M_\ast = 0.96^{+0.13}_{-0.09}$ $M_\odot$. The measured size of WASP-5b agrees well with the basic models of irradiated planets, while WASP-4b is clearly an “anomalously” large planet.


Key words: binaries: eclipsing -- planetary systems -- stars: individual: WASP-4 -- stars: individual: WASP-5 -- techniques: photometric -- techniques: spectroscopic



© ESO 2009

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.

Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

Mirror sites: CDS | EDP Sciences
  RSS feeds
© The European Southern Observatory (ESO)