A High-Resolution Spectroscopic Survey of Directly Imaged Companion Hosts: I. Determination of diagnostic stellar abundances for planet formation and composition

Abstract

We present the first results of an extensive spectroscopic survey of directly imaged planet host stars. The goal of the survey is the measurement of stellar properties and abundances of 15 elements (including C, O, and S) in these stars. In this work, we present the analysis procedure and the results for an initial set of five host stars, including some very well-known systems. We obtain C/O ratios using a combination of spectral modeling and equivalent width measurements for all five stars. Our analysis indicates solar C/O ratios for HR 8799 (0.59 $\pm$ 0.11), 51 Eri (0.54 $\pm$ 0.14), HD 984 (0.63 $\pm$ 0.14), and GJ 504 (0.54 $\pm$ 0.14). However, we find a super-solar C/O (0.81 $\pm$ 0.14) for HD 206893 through spectral modeling. The ratios obtained using the equivalent width method agree with those obtained using spectral modeling but have higher uncertainties ($\sim$0.3 dex). We also calculate the C/S and O/S ratios, which will help us to better constrain planet formation, especially once planetary sulfur abundances are measured using JWST. Lastly, we find no evidence of highly elevated metallicities or abundances for any of our targets, suggesting that a super metal-rich environment is not a prerequisite for large, widely separated gas planet formation. The measurement of elemental abundances beyond carbon and oxygen also provides access to additional abundance ratios, such as Mg/Si, which could aid in further modeling of their giant companions.

53 pages, 29 figures, 11 tables

References in corpus (53)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The chemical make-up of the Sun: A 2020 vision
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics From 10-100 AU
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• On the age of the $\beta$ Pictoris moving group
• Early Release Science of the exoplanet WASP-39b with JWST NIRSpec PRISM
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Early Release Science of the Exoplanet WASP-39b with JWST NIRSpec G395H
• Photochemically-produced SO${}_2$ in the atmosphere of WASP-39b
• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• Astrochemistry and compositions of planetary systems
• Retrieving scattering clouds and disequilibrium chemistry in the atmosphere of HR 8799e
• Tracing the formation history of giant planets in protoplanetary disks with Carbon, Oxygen, Nitrogen and Sulphur
• The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems II: A 1 to 20 Micron Spectrum of the Planetary-Mass Companion VHS 1256-1257 b
• How drifting and evaporating pebbles shape giant planets I: Heavy element content and atmospheric C/O
• Abundances in the Local Region II: F, G and K Dwarfs and Subgiants
• The 13O-rich atmosphere of a young accreting super-Jupiter
• Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD206893
• C/O Ratios of Stars with Transiting Hot Jupiter Exoplanets
• How drifting and evaporating pebbles shape giant planets II: Volatiles and refractories in atmospheres
• Chemical Diversity in Protoplanetary Disks and Its Impact on the Formation History of Giant Planets
• Gas composition of main volatile elements in protoplanetary discs and its implication for planet formation
• Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc
• Direct discovery of the inner exoplanet in the HD206893 system. Evidence for deuterium burning in a planetary-mass companion
• In-depth study of moderately young but extremely red, very dusty substellar companion HD206893B
• The Role of Ice Compositions for Snowlines and the C/N/O Ratios in Active Disks
• Three Super-Earths Orbiting HD 7924
• Stellar atmospheric parameters for 754 spectra from the X-shooter Spectral Library
• Deep exploration of the planets HR 8799 b, c, and d with moderate resolution spectroscopy
• Comet-like mineralogy of olivine crystals in an extrasolar proto-Kuiper belt
• Spitzer Follow-up of Extremely Cold Brown Dwarfs Discovered by the Backyard Worlds: Planet 9 Citizen Science Project
• Assessing the C/O Ratio Formation Diagnostic: A Potential Trend with Companion Mass
• Volatile-to-sulfur Ratios Can Recover a Gas Giant's Accretion History
• A critical reassessment of the fundamental properties of GJ 504: Chemical composition and age
• Connecting substellar and stellar formation. The role of the host star's metallicity
• Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances
• Peering into the Young Planetary System AB Pic. Atmosphere, Orbit, Obliquity & Second Planetary Candidate
• On the Chemical Abundance of HR 8799 and the Planet c
• Orbital and dynamical analysis of the system around HR 8799. New astrometric epochs from VLT/SPHERE and LBT/LUCI
• Retrieval study of cool, directly imaged exoplanet 51 Eri b
• Stellar Characterization of Keck HIRES Spectra with The Cannon
• Revisiting the atmosphere of the exoplanet 51 Eridani b with VLT/SPHERE
• The 3-D Kinematics of the Orion Nebula Cluster: NIRSPEC-AO Radial Velocities of the Core Population
• Moderate-Resolution $K$-Band Spectroscopy of Substellar Companion $\kappa$ Andromedae b
• Limits on the Mass and Initial Entropy of 51 Eri b from Gaia EDR3 Astrometry
• GRAVITY K-band spectroscopy of HD 206893 B: brown dwarf or exoplanet
• Chemical analysis of early-type stars with planets
• An updated visual orbit of the directly-imaged exoplanet 51 Eridani b and prospects for a dynamical mass measurement with Gaia
• The Influence of 10 Unique Chemical Elements in Shaping the Distribution of Kepler Planets
• RVSPY -- Radial Velocity Survey for Planets around Young Stars. Target characterization and high-cadence survey
• Fresh view of the hot brown dwarf HD 984 B through high-resolution spectroscopy
• Measuring the Stellar and Planetary Properties of the 51 Eridani System

Cited by in corpus (5)

• The compositions of the HR 8799 planets reflect accretion of both solids and metal-enriched gas
• Jupiter-like uniform metal enrichment in a system of multiple giant exoplanets
• A High-Resolution Spectroscopic Survey of Directly Imaged Companion Hosts: II. Diversity in C/O Ratios among Host Stars
• JWST-TST High Contrast: First Direct Spectroscopy of GJ 504 b reveals Clouds and Possible Metal Enrichment
• Observational imprints of tidal internal gravity wave dissipation in star-planet systems