Elodie metallicity-biased search for transiting Hot Jupiters I. Two Hot Jupiters orbiting the slightly evolved stars HD118203 and HD149143

TL;DR

This paper reports the discovery of two Hot Jupiters orbiting slightly evolved, metal-rich stars, HD118203 and HD149143, using radial velocity measurements, and discusses their orbital parameters and the absence of stellar activity influence.

Contribution

The study presents the detection of two new Hot Jupiters around metal-rich, slightly evolved stars, expanding the sample of such exoplanets and demonstrating the effectiveness of metallicity-biased searches.

Findings

HD118203 hosts a planet with P=6.13 days, e=0.31, m2sin(i)=2.1MJup.

HD149143 hosts a Hot Jupiter with P=4.09 days, e=0.08, m2sin(i)=1.36MJup.

Spectroscopic analysis confirms planetary origin of radial velocity signals.

Abstract

We report the discovery of a new planet candidate orbiting the subgiant star HD118203 with a period of P=6.1335 days. The best Keplerian solution yields an eccentricity e=0.31 and a minimum mass m2sin(i)=2.1MJup 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, HD149143, 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 1.36MJup. We checked that the shape of the spectral lines does not vary for this star as well.