EDP Sciences
Free access
Volume 485, Number 3, July III 2008
Page(s) 871 - 875
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20079238
Published online 15 May 2008

A&A 485, 871-875 (2008)
DOI: 10.1051/0004-6361:20079238

Improved parameters for the transiting planet HD 17156b: a high-density giant planet with a very eccentric orbit

M. Gillon1, A. H. M. J. Triaud1, M. Mayor1, D. Queloz1, S. Udry1, and P. North2

1  Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
    e-mail: michael.gillon@obs.unige.ch
2  Laboratoire d'Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland

Received 12 December 2007 / Accepted 12 April 2008

We report high-precision transit photometry for the recently detected planet HD 17156b. Using these new data with previously published transit photometry and radial velocity measurements, we perform a combined analysis based on a Markov Chain Monte Carlo approach. The resulting mass $M_{\rm p} = 3.09^{+0.22}_{-0.17}~M_{\rm Jup}$ and radius $R_{\rm p} = 1.23^{+0.17}_{-0.20}$  $R_{\rm Jup}$ for the planet places it at the outer edge of the density distribution of known transiting planets with $\rho_{\rm p} = 1.66^{+1.37}_{-0.60}$  $\rho_{\rm Jup}$. The obtained transit ephemeris is $T_{\rm Tr} = 2\,454\,438.48271^{+0.00077}_{-0.00057} + N \times 21.21747^{+0.00070}_{-0.00067}$ BJD. The derived plausible tidal circularization time scales for HD 17156b are larger than the age of the host star. The measured high orbital eccentricity e = 0.6719+0.0052-0.0063 can thus not be interpreted as the clear sign of the presence of another body in the system.

Key words: binaries: eclipsing -- planetary systems -- stars: individual: HD 17156 -- techniques: photometric

© ESO 2008