Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars

Abstract

CONTEXT. Exoplanet searches have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. AIMS. During the past six years, we have conducted a radial velocity follow-up program of 166 giant stars, to detect substellar companions, and characterizing their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions, and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. METHODS. Using FEROS and CHIRON spectra, we have computed precision radial velocities and we have derived atmospheric and physical parameters for all of our targets. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we have detected the presence of several substellar companions. RESULTS. We present four new planetary systems around the giant stars HIP8541, HIP74890, HIP84056 and HIP95124. Additionally, we find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of $f$ = 16.7${}_{-5.9}^{+15.5}$% around stars with [Fe/H] $\sim$ 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M${}_{\star }$ $\sim$ 1.0 -2.1 M${}_{\odot }$, with a maximum of $f$ = 13.0${}_{-4.2}^{+10.1}$%, at M${}_{\star }$ = 2.1 M${}_{\odot }$. CONCLUSIONS. We conclude that giant planets are preferentially formed around metal-rich stars. Also, we conclude that they are more efficiently formed around more massive stars, in the mass range of M${}_{\star }$ $\sim$ 1.0 - 2.1 M${}_{\odot }$. These observational results confirm previous findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model.

Accepted for publication in A&A

References in corpus (36)

• Validation of the new Hipparcos reduction
• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• No planet for HD 166435
• Giant Planet Occurrence in the Stellar Mass-Metallicity Plane
• Planet formation around stars of various masses: The snow line and the frequency of giant planets
• The metal-rich nature of stars with planets
• On the Estimation of Confidence Intervals for Binomial Population Proportions in Astronomy: The Simplicity and Superiority of the Bayesian Approach
• A New Planet Around an M Dwarf: Revealing a Correlation Between Exoplanets and Stellar Mass
• CHIRON - A Fiber Fed Spectrometer for Precise Radial Velocities
• Precise Radial Velocities of Giant Stars VII. Occurrence Rate of Giant Extrasolar Planets as a Function of Mass and Metallicity
• TW Hydrae: evidence of stellar spots instead of a Hot Jupiter
• Precise radial velocities of giant stars. III. Spectroscopic stellar parameters
• Planets around evolved intermediate-mass stars. I. Two substellar companions in the open clusters NGC 2423 and NGC 4349
• HAT-P-7: A Retrograde or Polar Orbit, and a Third Body
• Migration and giant planet formation
• Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars
• Evolved stars hint to an external origin of enhanced metallicity in planet-hosting stars
• Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
• Stellar parameters and chemical abundances of 223 evolved stars with and without planets
• Evidence for the Tidal Destruction of Hot Jupiters by Subgiant Stars
• Chromospheric Activities and Kinematics for Solar Type Dwarfs and Subgiants: Analysis of the Activity Distribution and the AVR
• Metallicities & Activities of Southern Stars
• The Pan-Pacific Planet Search. I. A Giant Planet Orbiting 7 CMa
• The properties of planets around giant stars
• The Anglo-Australian Planet Search. XXII. Two New Multi-Planet Systems
• Evidence against the young hot-Jupiter around BD +20 1790
• Retired A Stars and Their Companions IV. Seven Jovian Exoplanets from Keck Observatory
• The metallicity signature of evolved stars with planets
• Precise radial velocities of giant stars. IV. A correlation between surface gravity and radial velocity variation and a statistical investigation of companion properties
• Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. I. Sample definition and physical properties
• Are Stars with Planets Polluted?
• Planetary companions around the K giant stars 11 UMi and HD 32518
• Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP67851 c
• A planetary system and a highly eccentric brown dwarf around the giant stars HIP67851 and HIP97233
• Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. II. A giant planet in a close-in orbit around the RGB star HIP63242
• The Pan-Pacific Planet Search III: Five companions orbiting giant stars

Cited by in corpus (48)

• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• The Next Generation Transit Survey (NGTS)
• CERES: A Set of Automated Routines for Echelle Spectra
• Retired A Stars Revisited: An Updated Giant Planet Occurrence Rate as a Function of Stellar Metallicity and Mass
• 3-D selection of 167 sub-stellar companions to nearby stars
• Heavy metal rules. I. Exoplanet incidence and metallicity
• SPECIES I: Spectroscopic Parameters and atmosphEric ChemIstriEs of Stars
• A Tale of Planet Formation: From Dust to Planets
• New Planetary Systems from the Calan-Hertfordshire Extrasolar Planet Search
• Giant planet occurrence within 0.2 AU of low-luminosity red giant branch stars with K2
• Astrophysical Insights into Radial Velocity Jitter from an Analysis of 600 Planet-search Stars
• A wide-orbit giant planet in the high-mass b Centauri binary system
• Precise radial velocities of giant stars XVI. Planet occurrence rates from the combined analysis of the Lick, EXPRESS, and PPPS giant star surveys
• Lithium Enrichment Signatures of Planetary Engulfment Events in Evolved Stars
• Do close-in giant planets orbiting evolved stars prefer eccentric orbits?
• The Pan-Pacific Planet Search VII: The most eccentric planet orbiting a giant star
• The masses of retired A stars with asteroseismology: Kepler and K2 observations of exoplanet hosts
• An eccentric companion at the edge of the brown dwarf desert orbiting the 2.4 Msun giant star HIP67537
• Retired A Stars and Their Companions VIII: 15 New Planetary Signals Around Subgiants and Transit Parameters for California Planet Search Planets with Subgiant Hosts
• How Jupiters save or destroy inner Neptunes around evolved stars
• The Pan-Pacific Planet Search VI: Giant planets orbiting HD 86950 and HD 222076
• Giant planet engulfment by evolved giant stars: light curves, asteroseismology, and survivability
• The Pan-Pacific Planet Search. VIII. Complete results and the occurrence rate of planets around low-luminosity giants
• The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements
• The test case of HD26965: difficulties disentangling weak Doppler signals from stellar activity
• The Penn State - Toruń Centre for Astronomy Planet Search stars IV. Dwarfs and the complete sample
• Secular chaos in white-dwarf planetary systems: origins of metal pollution and short-period planetary companions
• Planets around the evolved stars 24 Booties and $\gamma$ Libra: A 30d-period planet and a double giant-planet system in possible 7:3 MMR
• Exoplanet Populations and their Dependence on Host Star Properties
• SPECIES II. Stellar parameters of the EXPRESS program giant star sample
• New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems
• Four Jovian planets around low-luminosity giant stars observed by the EXPRESS and PPPS
• Evidence of extra-mixing in field giants as traced by lithium and carbon isotope ratio
• TOI-1842b: A Transiting Warm Saturn Undergoing Re-Inflation around an Evolving Subgiant
• On the pollution of white dwarfs by exo-Oort cloud comets
• Regular Radial Velocity Variations in Nine G- and K-type Giant Stars: Eight Planets and One Planet Candidate
• The GALAH Survey: Using Galactic Archaeology to Refine our Knowledge of TESS Target Stars
• TESS Giants Transiting Giants V -- Two hot Jupiters orbiting red-giant hosts
• Planets around evolved intermediate-mass stars III. Planet candidates and long-term activity signals in six open clusters
• Spinning up a Daze: TESS Uncovers a Hot Jupiter orbiting the Rapid-Rotator TOI-778
• The California Legacy Survey II. Occurrence of Giant Planets Beyond the Ice line
• HD 83443c: A highly eccentric giant planet on a 22-year orbit
• Re-analysing the dynamical stability of the HD 47366 planetary system
• NGTS-21b: An Inflated Super-Jupiter Orbiting a Metal-poor K dwarf
• On the incidence of planet candidates in open clusters and a planet confirmation
• SAFARI I: A SPHERE discovery of a super metal-rich M dwarf companion to the star HD 86006
• A candidate giant planet companion to the massive, young white dwarf GALEX J071816.4+373139 informs the occurrence of giant planets orbiting B stars
• Companions to Kepler giant stars: A long-period eccentric substellar companion to KIC 3526061 and a stellar companion to HD 187878