Elodie metallicity-biased search for transiting Hot Jupiters

I. Two Hot Jupiters orbiting the slightly evolved stars HD 118203 and HD 149143

¹ Geneva Observatory, 1290 Sauverny, Switzerland e-mail: Ronaldo.daSilva@obs.unige.ch
² Observatoire de Marseille, France
³ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal
⁴ The Weizmann Institute of Science, PO Box 26, Rehovot 76100, Israel

Received: 29 August 2005
Accepted: 22 September 2005

Abstract

We report the discovery of a new planet candidate orbiting the subgiant star HD 118203 with a period of P = 6.1335 days. The best Keplerian solution yields an eccentricity e = 0.31 and a minimum mass = 2.1 M_Jup for the planet. This star has been observed with the ELODIE fiber-fed spectrograph as one of the targets in our planet-search programme biased toward high-metallicity stars, on-going since March 2004 at the Haute-Provence Observatory. An analysis of the spectroscopic line profiles using line bisectors revealed no correlation between the radial velocities and the line-bisector orientations, indicating that the periodic radial-velocity signal is best explained by the presence of a planet-mass companion. A linear trend is observed in the residuals around the orbital solution that could be explained by the presence of a second companion in a longer-period orbit. We also present here our orbital solution for another slightly evolved star in our metal-rich sample, HD 149143, recently proposed to host a 4-d period Hot Jupiter by the N2K consortium. Our solution yields a period P = 4.09 days, a marginally significant eccentricity e = 0.08 and a planetary minimum mass of 1.36 M_Jup. We checked that the shape of the spectral lines does not vary for this star as well.