Article (Scientific journals)
Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
Gillon, Michaël; Smalley, B.; Hebb, L. et al.
2009In Astronomy and Astrophysics, 496, p. 259-267
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Keywords :
binaries: eclipsing; planetary systems; stars: individual: WASP-4; stars: individual: WASP-5; techniques: photometric; techniques: spectroscopic
Abstract :
[en] 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[SUB]p[/SUB] = 1.30[SUP]+0.05[/SUP][SUB]-0.04[/SUB] R[SUB]J[/SUB] and M[SUB]p[/SUB] = 1.21[SUP]+0.13[/SUP][SUB]-0.08[/SUB] M_J, resulting in a density rho[SUB]p[/SUB] = 0.55[SUP]+0.04[/SUP][SUB]-0.02[/SUB] rho_J. The radius and mass for the host star are R_* = 0.87[SUP]+0.04[/SUP][SUB]-0.03[/SUB] R_o and M_* = 0.85[SUP]+0.11[/SUP][SUB]-0.07[/SUB] M_o. 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[SUB]p[/SUB] = 1.09 ± 0.07 R_J, M[SUB]p[/SUB] = 1.58[SUP]+0.13[/SUP][SUB]-0.10[/SUB] M_J, rho[SUB]p[/SUB] = 1.23 [SUP]+0.26[/SUP][SUB]-0.16[/SUB] rho_J, R_* = 1.03[SUP]+0.06[/SUP][SUB]-0.07[/SUB] R_o, and M_* = 0.96[SUP]+0.13[/SUP][SUB]-0.09[/SUB] M_o. The measured size of WASP-5b agrees well with the basic models of irradiated planets, while WASP-4b is clearly an ``anomalously'' large planet. Based on data collected with the FORS2 imager at the VLT-UT4 telescope and with the UVES spectrograph at the VLT-UT2 telescope (Paranal Observatory, ESO, Chile) in the programme 280.C-5003.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Gillon, Michaël  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Smalley, B.;  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Hebb, L.;  School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
Anderson, D. R.;  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Triaud, A H M J;  Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
Hellier, C.;  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Maxted, P. F. L.;  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Queloz, D.;  Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
Wilson, D. M.;  Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Language :
English
Title :
Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b
Publication date :
01 March 2009
Journal title :
Astronomy and Astrophysics
ISSN :
0004-6361
eISSN :
1432-0746
Publisher :
EDP Sciences, Les Ulis, France
Volume :
496
Pages :
259-267
Peer reviewed :
Peer Reviewed verified by ORBi
Commentary :
http://de.arxiv.org/abs/0812.1998
Available on ORBi :
since 30 October 2009

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