Lithium Enrichment Signatures of Planetary Engulfment Events in Evolved Stars

Abstract

Planetary engulfment events have long been proposed as a lithium (Li) enrichment mechanism contributing to the population of Li-rich giants (A(Li) >= 1.5 dex). Using MESA stellar models and A(Li) abundance measurements obtained by the GALAH survey, we calculate the strength and observability of the surface Li enrichment signature produced by the engulfment of a hot Jupiter (HJ). We consider solar-metallicity stars in the mass range of 1-2 ${\mathrm{M}}_{\odot }$ and the Li supplied by a HJ of 1.0 ${\mathrm{M}}_{\mathrm{J}}$. We explore engulfment events that occur near the main sequence turn-off (MSTO) and out to orbital separations of 0.1 AU. We map our results onto the Hertzsprung-Russell Diagram, revealing the statistical significance and survival time of lithium enrichment. We identify the parameter space of masses and evolutionary phases where the engulfment of a HJ can lead to Li enrichment signatures at a $5\sigma$ confidence level and with meteoritic abundance strengths. The most compelling strengths and survival times of engulfment-derived Li enrichment are found among host stars of 1.4 ${\mathrm{M}}_{\odot }$ near the MSTO. Our calculations indicate that planetary engulfment is not a viable enrichment pathway for stars that have evolved beyond the subgiant branch. For these sources, observed Li enhancements are likely to be produced by other mechanisms, such as the Cameron-Fowler process or the accretion of material from an asymptotic giant branch (AGB) companion. Our results do not account for second-order effects, such as extra mixing processes, which can further dilute Li enrichment signatures.

arXiv comment18 pages, 8 figures

References in corpus (98)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The NumPy array: a structure for efficient numerical computation
• The chemical composition of the Sun
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• The Occurrence and Architecture of Exoplanetary Systems
• Giant Planet Occurrence in the Stellar Mass-Metallicity Plane
• Gaia Data Release 2: first stellar parameters from Apsis
• The Cannon: A data-driven approach to stellar label determination
• Influence of gravity waves on the internal rotation and Li abundance of solar-type stars
• The GALAH Survey: Second Data Release
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• The Orbital Evolution of Gas Giant Planets around Giant Stars
• Thermohaline instability and rotation-induced mixing. I - Low- and intermediate-mass solar metallicity stars up to the end of the AGB
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
• The Payne: self-consistent ab initio fitting of stellar spectra
• Standard Solar models in the Light of New Helioseismic Constraints II. Mixing Below the Convective Zone
• Hot Jupiters and Cool Stars
• Retired A Stars and Their Companions. III. Comparing the Mass-Period Distributions of Planets Around A-Type Stars and Sun-Like Stars
• Deep learning of multi-element abundances from high-resolution spectroscopic data
• Enhanced lithium depletion in Sun-like stars with orbiting planets
• Accuracy and precision of industrial stellar abundances
• The Orbit of WASP-12b is Decaying
• Lithium depletion in solar-like stars: no planet connection
• The Accretion of Brown Dwarfs and Planets by Giant Stars -- I. AGB Stars
• Can Extra Mixing in RGB and AGB Stars Be Attributed to Magnetic Mechanisms?
• Lithium in stars with exoplanets
• Isochrone ages for ~3 million stars with the second Gaia data release
• Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013)
• Origin of lithium enrichment in K giants
• Lithium Depletion in Fully Convective Pre-Main Sequence Stars
• Kepler-91b: a planet at the end of its life. Planet and giant host star properties via light-curve variations
• Li depletion in solar analogues with exoplanets: Extending the sample
• Lithium Depletion in Pre-Mainsequence Solar-Like Stars
• Hydrodynamic Simulations of the Interaction between Giant Stars and Planets
• High Precision Abundances of the Old Solar Twin HIP 102152: Insights on Li Depletion from the Oldest Sun
• On Lithium-Rich Red Giants. I. Engulfment of Sub-Stellar Companions
• Magnetic Mixing in Red Giant and Asymptotic Giant Branch Stars
• A Hot Saturn Orbiting An Oscillating Late Subgiant Discovered by TESS
• Correlation between lithium abundances and ages of solar twin stars
• Thermohaline mixing in evolved low-mass stars
• Radial Velocity Observations and Light Curve Noise Modeling Confirm That Kepler-91b is a Giant Planet Orbiting a Giant Star
• Early optical spectra of nova V1369 Cen show presence of Lithium
• Magneto-Thermohaline Mixing in Red Giants
• Tidal interactions between binary stars drives lithium production in low-mass red giants
• Seeing double with K2: Testing re-inflation with two remarkably similar planets around red giant branch stars
• Age and mass of solar twins constrained by lithium abundance
• The Role of Planet Accretion in Creating the Next Generation of Red Giant Rapid Rotators
• Star-planet interactions: II. Is planet engulfment the origin of fast rotating red giants?
• On the Numerical Treatment and Dependence of Thermohaline Mixing in Red Giants
• Lithium-Rich Giants in Globular Clusters
• Lithium-Rich Field Giants in the Sloan Digital Sky Survey
• K2-97b: A (Re-?)Inflated Planet Orbiting a Red Giant Star
• Four new planets around giant stars and the mass-metallicity correlation of planet-hosting stars
• Lithium-rich giants in the Galactic thick disk
• The nature of the Li enrichment in the most Li-rich giant star
• Highly Enriched 7Be in the ejecta of Nova Sagittarii 2015 No. 2 (V5668 Sgr) and the Galactic Lithium origin
• HD 1397b: a transiting warm giant planet orbiting a V = 7.8 mag sub-giant star discovered by TESS
• The Li-age correlation: the Sun is unusually Li deficient for its age
• An Eccentric Massive Jupiter Orbiting a Sub-Giant on a 9.5 Day Period Discovered in the Transiting Exoplanet Survey Satellite Full Frame Images
• A-type Stars, the Destroyers of Worlds: The lives and deaths of Jupiters in evolving stellar binaries
• BD+48 740 - Li overabundant giant star with a planet. A case of recent engulfment?
• Lithium-rich Giants in LAMOST Survey. I. The Catalog
• Three Li-rich K giants: IRAS 12327-6523, IRAS 13539-4153, and IRAS 17596-3952
• Planet accretion and the abundances of lithium isotopes
• A Jovian planet in an eccentric 11.5 day orbit around HD1397 discovered by TESS
• Survey of Li-rich giants among Kepler and LAMOST fields: Determination of Li-rich giants Evolutionary Phase
• The Lithium Flash - Thermal instabilities generated by lithium burning in RGB stars
• The Penn State - Torun Centre for Astronomy Planet Search stars. II. Lithium abundance analysis of the Red Giant Clump sample
• Enormous Li-enhancement preceding red giant phases in low-mass stars in the Milky Way halo
• Population synthesis of helium white dwarf--red giant star mergers and the formation of lithium-rich giants and carbon stars
• A super lithium-rich red-clump star in the open cluster Trumpler 5
• Study of Lithium Rich Giants with the GALAH Spectroscopic Survey
• An Ultra-High-Resolution Survey of the Interstellar ^7Li-to-^6Li Isotope Ratio in the Solar Neighborhood
• The Super Lithium-Rich Red Giant Rapid Rotator G0928+73.2600: A Case for Planet Accretion?
• Eating Planets for Lunch and Dinner: Signatures of Planet Consumption by Evolving Stars
• The K2-ESPRINT Project V: a short-period giant planet orbiting a subgiant star
• Lithium abundances along the RGB: FLAMES-GIRAFFE spectra of a large sample of low-mass Bulge stars
• Planetary Engulfment in the Hertzsprung--Russell Diagram
• Do close-in giant planets orbiting evolved stars prefer eccentric orbits?
• HIP 114328: a new refractory-poor and Li-poor solar twin
• The Effects of Planets and Brown Dwarfs on Stellar Rotation and Mass-Loss
• Lithium abundance and rotation of seismic solar analogues - Solar and stellar connection from Kepler and Hermes observations
• TAPAS - Tracking Advanced Planetary Systems with HARPS-N. II. Super Li-rich giant HD 107028
• On Lithium-Rich Red Giants. II. Engulfment on the Giant Branch of Trumpler 20
• Signature of Planetary Mergers on Stellar Spins
• Evolution of lithium abundance in the Sun and solar twins
• Disruption of a planet spiralling into its host star
• Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. VI. HD 238914 and TYC 3318-01333-1 - two more Li-rich giants with planets
• High-resolution spectroscopic analysis of a large sample of Li-rich giants found by LAMOST
• The Gaia-ESO Survey: Inhibited extra mixing in two giants of the open cluster Trumpler 20?
• Overshooting by convective settling
• HD 16771: A lithium-rich giant in the red-clump stage

Cited by in corpus (8)

• Asteroseismic Fingerprints of Stellar Mergers
• Hydrodynamics and survivability during post-main-sequence planetary engulfment
• Evidence of extra-mixing in field giants as traced by lithium and carbon isotope ratio
• Li-rich Giants in LAMOST Survey. III. The statistical analysis of Li-rich giants
• An unsupervised method for identifying $X$-enriched stars directly from spectra: Li in LAMOST
• Hot Jupiter engulfment by a red giant in 3D hydrodynamics
• Sub-stellar engulfment by a main sequence star: where is the lithium?
• WIYN Open Cluster Study LXXXI. Caught in the Act? The Peculiar Red Giant NGC 2243-W2135