The HARPS search for southern extra-solar planets

Abstract

We are conducting a planet search survey with HARPS since seven years. The volume-limited stellar sample includes all F2 to M0 main-sequence stars within 57.5 pc, where extrasolar planetary signatures are systematically searched for with the radial-velocity technics. In this paper, we report the discovery of new substellar companions of seven main-sequence stars and one giant star, detected through multiple Doppler measurements with the instrument HARPS installed on the ESO 3.6 m telescope, La Silla, Chile. These extrasolar planets orbit the stars HD 1690, HD 25171, HD 33473A, HD 89839, HD 113538, HD 167677, and HD 217786. The alreadypublished giant planet around HD 72659 is also analysed here, and its elements are better determined by the addition of HARPS and Keck data. The other discoveries are giant planets in distant orbits, ranging from 0.3 to 29 M Jup in mass and between 0.7 and 10 years in orbital period. The low metallicity of most of these new planet-hosting stars reinforces the current trend for long-distance planets around metal-poor stars. Long-term radial-velocity surveys allow probing the outskirts of extrasolar planetary systems, although confidence in the solution may be low until more than one orbital period is fully covered by the observations. For many systems discussed in this paper, longer baselines are necessary to refine the radial-velocity fit and derive planetary parameters. The radial-velocity time series of stars BD -114672 and HIP 21934 are also analysed and their behaviour interpreted in terms of the activity cycle of the star, rather than long-period planetary companions.

The HARPS search for southern extra-solar planets

“…We present here an update of the analysis of HARPS measurements of HD 113538, in which two planets were already reported in Moutou et al (2011). We have now collected 75 HARPS measurements of HD 113538, spanning 3700 days, while there were only 29 (over 2268 days) in the previous study and much uncertainty remained on the parameters of these companions.…”

“…All parameters are listed in Table 1. For HD 113538 and BD -114672, updates are provided for the spectroscopic analysis, and in addition, masses (and radii and ages) have been corrected from the erroneous values given in Moutou et al (2011); these incorrect mass values were due to missing information in the evolutionary track interface for low-mass stars, which are solved now (Chen et al 2014). Activity indicators (S MW and log R HK ) were individually estimated on each spectrum, and their range of values is given in Table 1.…”

“…The symbol color indicates the discovery method (blue: direct imaging; orange: RV; green: transits; black: microlenses). for which the best-fit parameters are refined, and BD -114672, whose signal was previously identified to be due to a long-term magnetic cycle (Moutou et al 2011). Host stars are described in Sect.…”

Precise determination of fundamental parameters of six exoplanet host stars and their planets

“…Vogt et al , 2000;Pietrukowicz et al , 2010;Moutou et al , 2011;Ofir & Dreizler , 2013;Rowe et al , 2014). An overwhelming majority of them have been discovered using indirect methods, i.e., radial-velocity (RV) and photometric transits.…”

Magnetism and activity of planet hosting stars

“…Moutou et al (2011) (2008), illustrating the strange case of HD 154345, purportedly the first good Jupiter analog. The apparently strong and clean RV signal is clearly well correlated with the Mount Wilson S index, a measurement of chromospheric activity (circles, bottom).…”