Occurrence rates of small planets from HARPS: Focus on the Galactic context

Abstract

Context. The stars in the Milky Way thin and thick disks can be distinguished by several properties such as metallicity and kinematics. It is not clear whether the two populations also differ in the properties of planets orbiting the stars. In order to study this, a careful analysis of both the chemical composition and mass detection limits is required for a sufficiently large sample. Currently, this information is still limited only to large radial-velocity (RV) programs. Based on the recently published archival database of the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph, we present a first analysis of low-mass (small) planet occurrence rates in a sample of thin- and thick-disk stars. Aims. We aim to assess the effects of stellar properties on planet occurrence rates and to obtain first estimates of planet occurrence rates in the thin and thick disks of the Galaxy. As a baseline for comparison, we also aim to provide an updated value for the small close-in planet occurrence rate and compare it to results of previous RV and transit ($\text{Kepler}$) works. Methods. We used archival HARPS RV datasets to calculate detection limits of a sample of stars that were previously analysed for their elemental abundances. For stars with known planets we first subtracted the Keplerian orbit. We then used this information to calculate planet occurrence rates according to a simplified Bayesian model in different regimes of stellar and planet properties. Results. Our results suggest that metal-poor stars and more massive stars host fewer low-mass close-in planets. We find the occurrence rates of these planets in the thin and thick disks to be comparable. In the iron-poor regimes, we find these occurrence rates to be significantly larger at the high-$\alpha$ region (thick-disk stars) as compared with the low-$\alpha$ region (thin-disk stars). In general, we find the...

arXiv comment10 pages, 6 figures, accepted for publication in A&A

References in corpus (59)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Transiting Exoplanet Survey Satellite
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• Spectroscopic [Fe/H] for 98 extra-solar planet-host stars: Exploring the probability of planet formation
• Elemental Abundance Survey of The Galactic Thick Disk
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• Giant Planet Occurrence in the Stellar Mass-Metallicity Plane
• Defining and cataloging exoplanets: The exoplanet.eu database
• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program.Galactic stellar populations and planets
• The GALAH Survey: Second Data Release
• Terrestrial Planet Occurrence Rates for the Kepler GK Dwarf Sample
• The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets
• Statistical properties of exoplanets II. Metallicity, orbital parameters, and space velocities
• Exoplanet population inference and the abundance of Earth analogs from noisy, incomplete catalogs
• Revisited Mass-Radius relations for exoplanets below 120 Earth masses
• An Increase in the Mass of Planetary Systems around Lower-Mass Stars
• The Exoplanet Census: A General Method, Applied to Kepler
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu
• Abundance Estimates for 16 Elements in 6 Million Stars from LAMOST DR5 Low-Resolution Spectra
• Occurrence Rates of Planets orbiting FGK Stars: Combining Kepler DR25, Gaia DR2 and Bayesian Inference
• An Excess of Jupiter Analogs in Super-Earth Systems
• A new alpha-enhanced super-solar metallicity population
• The Super Earth-Cold Jupiter Relations
• A public HARPS radial velocity database corrected for systematic errors
• Disentangling the Galactic Halo with APOGEE: I. Chemical and Kinematical Investigation of Distinct Metal-Poor Populations
• Exploring the alpha-enhancement of metal-poor planet-hosting stars. The Kepler and HARPS samples
• Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307
• Overabundance of alpha-elements in exoplanet host stars
• Occurrence Rates of Planets Orbiting M Stars: Applying ABC to Kepler DR25, Gaia DR2, and 2MASS Data
• Two Empirical Regimes of the Planetary Mass-Radius Relation
• Constraining planet structure and composition from stellar chemistry: trends in different stellar populations
• Orbital and physical properties of planets and their hosts: new insights on planet formation and evolution
• Color difference makes a difference: four planet candidates around tau Ceti
• The HARPS search for southern extrasolar planets XXV. Results from the metal-poor sample
• On the correlation between metallicity and the presence of giant planets
• TESS delivers its first Earth-sized planet and a warm sub-Neptune
• The planet search program at the ESO Coude Echelle spectrometer. III. The complete Long Camera survey results
• Improving the Accuracy of Planet Occurrence Rates from Kepler using Approximate Bayesian Computation
• The HARPS search for southern extra-solar planets. XXXVI. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions
• The HARPS search for southern extra-solar planets. XLIII. A compact system of four super-Earth planets orbiting HD 215152
• Agatha: disentangling periodic signals from correlated noise in a periodogram framework
• Comparison of different exoplanet mass detection limit methods using a sample of main-sequence intermediate-type stars
• The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap
• Exploring the realm of scaled Solar System analogs with HARPS
• Radial velocities from the N2K Project: 6 new cold gas giant planets orbiting HD 55696, HD 98736, HD 148164, HD 203473, and HD 211810
• Influence of Stellar Metallicity on Occurrence Rates of Planets and Planetary Systems
• Extrasolar planets and brown dwarfs around AF-type stars. IX. The HARPS southern sample
• TESS exoplanet candidates validated with HARPS archival data. A massive Neptune around GJ143 and two Neptunes around HD23472
• The HARPS search for southern extra-solar planets. XXXIX. HD175607 b, the most metal-poor G dwarf with an orbiting sub-Neptune
• Beyond the exoplanet mass-radius relation
• The Metallicity-Period-Mass Diagram of low-mass exoplanets
• Small Planets in the Galactic Context: Host Star Kinematics, Iron, and $\alpha$ Element Enhancement
• Variations in $\alpha$-element ratios trace the chemical evolution of the disk
• The HARPS search for southern extra-solar planets XL. Searching for Neptunes around metal-poor stars
• A Quantitative Comparison of Exoplanet Catalogs

Cited by in corpus (12)

• Exoplanets in the Galactic context: Planet occurrence rates in the thin disk, thick disk and stellar halo of Kepler stars
• Elemental abundances of nearby M dwarfs based on high-resolution near-infrared spectra obtained by the Subaru/IRD survey: Proof of concept
• Ariel stellar characterisation: I -- homogeneous stellar parameters of 187 FGK planet host stars Description and validation of the method
• Energetic particle activity in AD Leo: Detection of a solar-like type-IV burst
• How the origin of stars in the Galaxy impacts the composition of planetary building blocks
• Exoplanets Across Galactic Stellar Populations with PLATO: Estimating Exoplanet Yields Around FGK Stars for the Thin Disk, Thick Disk and Stellar Halo
• Populating The Milky Way: Characterising Planet Demographics by Combining Galaxy Formation Simulations and Planet Population Synthesis Models
• EMISSA -- Exploring Millimetre Indicators of Solar-Stellar Activity II. Towards a robust indicator of stellar activity
• Quantifying chemical and kinematical properties of Galactic disks
• Modelling the Milky Way's exoplanet population based on cosmological galaxy simulations
• Stellar chemistry and planet size: insights from GALAH DR4
• Role of non-thermal processes in the quiescent and active millimeter spectrum of a young M dwarf