The Curious Case of Elemental Abundance Differences in the Dual Hot Jupiter Hosts WASP-94AB

Abstract

Binary stars provide an ideal laboratory for investigating the potential effects of planet formation on stellar composition. Assuming the stars formed in the same environment/from the same material, any compositional anomalies between binary components might indicate differences in how material was sequestered in planets, or accreted by the star in the process of planet formation. We present here a study of the elemental abundance differences between WASP-94AB, a pair of stars that each host a hot Jupiter exoplanet. The two stars are very similar in spectral type (F8 and F9), and their ~2700 AU separation suggests their protoplanetary disks were likely not influenced by stellar interactions, but WASP-94Ab's orbit -- misaligned with the host star spin axis and likely retrograde -- points towards a dynamically active formation mechanism, perhaps different than that of WASP-94Bb, which is not misaligned and has nearly circular orbit. Based on our high-quality spectra and strictly relative abundance analysis, we detect a depletion of volatiles (~-0.02 dex, on average) and enhancement of refractories (~0.01 dex) in WASP-94A relative to B (standard errors are ~0.005 dex). This is different than every other published case of binary host star abundances, in which either no significant abundance differences are reported, or there is some degree of enhancement in all elements, including volatiles. Several scenarios that may explain the abundance trend are discussed, but none can be definitively accepted or rejected. Additional high-contrast imaging observations to search for companions that may be dynamically affecting the system, as well as a larger sample of binary host star studies, are needed to better understand the curious abundance trends we observe in WASP-94AB.

Accepted to ApJ 7 Jan 2016. 21 pages, 5 figures, 3 Tables (1 MRT)

References in corpus (30)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Dynamical Outcomes of Planet-Planet Scattering
• Spectroscopic parameters for 451 stars in the HARPS GTO planet search program. Stellar [Fe/H] and the frequency of exo-Neptunes
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
• Stellar Parameters and Metallicities of Stars Hosting Jovian and Neptunian Mass Planets: A Possible Dependence of Planetary Mass on Metallicity
• Oxygen Abundances in Nearby Stars. Clues to the formation and evolution of the Galactic disk
• XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary
• Lithium depletion and the rotational history of exoplanet host stars
• Li abundances in F stars: planets, rotation and galactic evolution
• The Metallicities of Stars With and Without Transiting Planets
• High eccentricity planets from the Anglo-Australian Planet Search
• The dissimilar chemical composition of the planet-hosting stars of the XO-2 binary system
• On the origin of stars with and without planets. Tc trends and clues to Galactic evolution
• C/O Ratios of Stars with Transiting Hot Jupiter Exoplanets
• High precision abundances in the 16 Cyg binary system: a signature of the rocky core in the giant planet
• A high precision chemical abundance analysis of the HAT-P-1 stellar binary: constraints on planet formation
• Homogeneous abundance analysis of dwarf, subgiant and giant FGK stars with and without giant planets
• Abundance Differences Between Exoplanet Binary Host Stars XO-2N and XO-2S -- Dependence on Stellar Parameters
• What are little worlds made of? Stellar abundances and the building blocks of planets
• WASP-94 A and B planets: hot-Jupiter cousins in a twin-star system
• Detailed Abundances of Planet-Hosting Wide Binaries. I. Did Planet Formation Imprint Chemical Signatures in the Atmospheres of HD 20782/81?
• Parent Stars of Extrasolar Planets. IX. Lithium Abundances
• The GAPS Programme with HARPS-N@TNG V. A comprehensive analysis of the XO-2 stellar and planetary systems
• The GAPS programme with HARPS-N@TNG IV: A planetary system around XO-2S
• The Fate of Scattered Planets
• Parent Stars of Extrasolar Planets - XIII. Additional Evidence for Li Abundance Anomalies
• HD 80606: Searching the chemical signature of planet formation
• Exoplanet hosts reveal lithium depletion: Results from a homogeneous statistical analysis
• Granulation in K-type Dwarf Stars. I. Spectroscopic observations

Cited by in corpus (45)

• The Chemical Homogeneity of Sun-like Stars in the Solar Neighborhood
• High-precision stellar abundances of the elements - methods and applications
• Identical or fraternal twins? : The chemical homogeneity of wide binaries from Gaia DR2
• Kronos & Krios: Evidence for accretion of a massive, rocky planetary system in a comoving pair of solar-type stars
• The SPHINX M-dwarf Spectral Grid. I. Benchmarking New Model Atmospheres to Derive Fundamental M-Dwarf Properties
• High-precision abundances of elements in Kepler LEGACY stars. Verification of trends with stellar age
• How magnetic activity alters what we learn from stellar spectra
• Chemical evidence for planetary ingestion in a quarter of Sun-like stars
• The Solar Twin Planet Search. V. Close-in, low-mass planet candidates and evidence of planet accretion in the solar twin HIP 68468
• The chemical composition of HIP34407/HIP34426 and other twin-star comoving pairs
• Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances
• The Magellan PFS Planet Search Program: Radial Velocity and Stellar Abundance Analyses of the 360 AU, Metal-Poor Binary "Twins" HD 133131A & B
• Revisiting the 16 Cygni planet host at unprecedented precision and exploring automated tools for precise abundances
• Revisiting the pre-main-sequence evolution of stars II. Consequences of planet formation on stellar surface composition
• ${\zeta }^2$ Ret, its debris disk, and its lonely stellar companion ${\zeta }^1$ Ret. Different $T_{\mathrm{c}}$ trends for different spectra
• Distant Relatives: The Chemical Homogeneity of Comoving Pairs Identified in Gaia
• Evidence for an Optical Low-frequency Quasi-Periodic Oscillation in the Kepler Light Curve of an Active Galaxy
• Detailed chemical compositions of the wide binary HD 80606/80607: revised stellar properties and constraints on planet formation
• Abundance trend with condensation temperature for stars with different Galactic birth places
• Planet Engulfment Detections are Rare According to Observations and Stellar Modeling
• Behaviour of elements from lithium to europium in stars with and without planets
• LRG-BEASTS: sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2
• Chemical inhomogeneities in the Pleiades: signatures of rocky-forming material in stellar atmospheres
• Detailed elemental abundances of binary stars: Searching for signatures of planet formation and atomic diffusion
• Planet Engulfment Signatures in Twin Stars
• High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP). II. Lucky Imaging results from 2015 and 2016
• How does accretion of planet-forming disks influence stellar abundances?
• Very wide companion fraction from Gaia DR2: a weak or no enhancement for hot jupiter hosts, and a strong enhancement for contact binaries
• The chemical composition of $\alpha$ Cen AB revisited
• High-precision analysis of binary stars with planets. I. Searching for condensation temperature trends in the HD 106515 system
• Evidences of extragalactic origin and planet engulfment in the metal-poor twin pair HD 134439/HD 134440
• Many Roads Lead to Lithium: Formation Pathways For Lithium-Rich Red Giants
• Dust cleansing of star-forming gas I: Did radiation from bright stars affect the chemical composition of the Sun and of M67?
• Statistics of the Chemical Composition of Solar Analog Stars and Links to Planet Formation
• Super-Earth ingestion can explain the anomalously high metal abundances of M67 Y2235
• Dust cleansing of star-forming gas: II. Did late accretion flows change the chemical composition of the solar atmosphere?
• Stellar abundance of binary stars: their role in determining the formation location of super-Earths and ice giants
• The consistency of chemical clocks among coeval stars
• The peculiar chemical pattern of the WASP-160 binary system: signatures of planetary formation and evolution?
• Tracing the formation and migration history: molecular signatures in the atmosphere of misaligned hot Jupiter WASP-94Ab using JWST NIRSpec/G395H
• Sun-like stars unlike the Sun: Clues for chemical anomalies of cool stars
• Dust-Evacuated Zones Near Massive Stars: Consequences of Dust Dynamics on Star-forming Regions
• Planet Hunters TESS V: a planetary system around a binary star, including a mini-Neptune in the habitable zone
• DIAmante TESS AutoRegressive Planet Search (DTARPS): II. Hundreds of New TESS Candidate Exoplanets
• Elemental Abundances of Kepler Objects of Interest in APOGEE DR17