Lithium in Open Cluster Red Giants Hosting Substellar Companions

Abstract

We have measured stellar parameters, [Fe/H], lithium abundances, rotation, and 12C/13C in a small sample of red giants in three open clusters that are each home to a red giant star that hosts a substellar companion (NGC2423 3, NGC4349 127, and BD+12 1917 in M67). Our goal is to explore whether the presence of substellar companions influences the Li content. Both 12C/13C and stellar rotation are measured as additional tracers of stellar mixing. One of the companion hosts, NGC2423 3, is found to be Li-rich with A(Li)_NLTE=1.56 dex, and this abundance is significantly higher than the A(Li) of the two comparison stars in NGC2423. All three substellar companion hosts have the highest A(Li) and 12C/13C when compared to the control red giants in their respective clusters; however, except for NGC2423 3, at least one control star has similarly high abundances within the uncertainties. Higher A(Li) could suggest that the formation or presence of planets plays a role in the degree of internal mixing on or before the red giant branch. However, a multitude of factors affect A(Li) during the red giant phase, and when the abundances of our sample are compared to abundances of red giants in other open clusters available in the literature, we find that they all fall well within a much larger distribution of A(Li) and 12C/13C. Thus, even the high Li in NGC2423 3 cannot be concretely tied to the presence of the substellar companion.

10 pages; Accepted for publication in ApJ

References in corpus (17)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Basic physical parameters of a selected sample of evolved stars
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• 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
• Stellar parameters and chemical abundances of 223 evolved stars with and without planets
• Observable Signatures of Planet Accretion in Red Giant Stars I: Rapid Rotation and Light Element Replenishment
• Metallicities of Planet Hosting Stars: A Sample of Giants and Subgiants
• Rapid Rotation of Low-Mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence
• MARCS model atmospheres
• Lithium Abundances in a Sample of Planet Hosting Dwarfs
• The Penn State - Torun Centre for Astronomy Planet Search stars. II. Lithium abundance analysis of the Red Giant Clump sample
• A super lithium-rich red-clump star in the open cluster Trumpler 5
• Parent Stars of Extrasolar Planets - XIII. Additional Evidence for Li Abundance Anomalies
• The Puzzling Li-rich Red Giant Associated with NGC 6819
• The Chemical Compositions and Evolutionary Status of Red Giants in the Open Cluster NGC 752
• Complex Organic and Inorganic Compounds in Shells of Lithium-rich K Giant Stars

Cited by in corpus (13)

• Surface rotation of Kepler red giant stars
• On Lithium-Rich Red Giants. I. Engulfment of Sub-Stellar Companions
• The Gaia-ESO Survey: properties of newly discovered Li-rich giants
• Chemical Abundances in a Sample of Red Giants in the Open Cluster NGC 2420 from APOGEE
• Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. VI. HD 238914 and TYC 3318-01333-1 - two more Li-rich giants with planets
• The Gaia-ESO Survey: Inhibited extra mixing in two giants of the open cluster Trumpler 20?
• On the role of reduced wind mass-loss rate in enabling exoplanets to shape planetary nebulae
• Probing infrared excess connection with Li enhancement among red clump giants
• Lithium Inventory of 2 $M_{\odot }$ Red Clump Stars in Open Clusters: A Test of the Helium Flash Mechanism
• On Lithium-6 as diagnostic of the lithium-enrichment mechanism in red giants
• Detection of Open Cluster Members Inside and Beyond Tidal Radius by Machine Learning Methods Based on Gaia DR3
• Non-radial oscillations mimicking a brown dwarf orbiting the cluster giant NGC 4349 No. 127
• Rapid expansion of red giant stars during core helium flash by waves propagation to the envelope and implications to exoplanets