RAFT - I. Discovery of new planetary candidates and updated orbits from archival FEROS spectra

Abstract

A recent reanalysis of archival data has lead several authors to arrive at strikingly different conclusions for a number of planet-hosting candidate stars. In particular, some radial velocities (RVs) measured using Fiber-fed Extended Range Optical Spectrograph (FEROS) spectra have been shown to be inaccurate, throwing some doubt on the validity of a number of planet detections. Motivated by these results, we have begun the Reanalysis of Archival FEROS specTra (RAFT) programme and here we discuss the first results from this work. We have reanalyzed FEROS data for the stars HD 11977, HD 47536, HD 70573, HD 110014 and HD 122430, all of which are claimed to have at least one planetary companion. We have reduced the raw data and computed the radial velocity variations of these stars, achieving a long-term precision of ~10ms-1 on the known stable star τ Ceti, and in good agreement with the residuals to our fits. We confirm the existence of planets around HD 11977, HD 47536 and HD 110014, but with different orbital parameters than those previously published. In addition, we found no evidence of the second planet candidate around HD 47536, nor any companions orbiting HD 122430 and HD 70573. Finally, we report the discovery of a second planet around HD 110014, with a minimum mass of 3.1MJup and a orbital period of 130 d. Analysis of activity indicators allows us to confirm the reality of our results and also to measure the impact of magnetic activity on our RV measurements. These results confirm that very metal poor stars down to [Fe/H]~-0.7 dex, can indeed form giant planets given the right conditions.