Super lithium-rich K giant with low ${}^{12}\mathrm{C}$ to ${}^{13}\mathrm{C}$ ratio

Abstract

The lithium abundances in a few percent of giants exceed the value predicted by the standard stellar evolution models, and the mechanisms of Li enhancement are still under debate. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey has obtained over six million spectra in the past five years, and thus provides a great opportunity to search these rare objects and to more clearly understand the mechanisms of Li enhancement. Based on the high-resolution spectrum we obtained the stellar parameters ($T_{\mathrm{eff}}$, $\log g$, [Fe/H]), and determined the elemental abundances of Li, C, N, $\alpha$, Fe-peak, r-process, s-process elements, and the projected rotational velocity. For a better understanding of the effect of mixing processes, we also derived the ${}^{12}\mathrm{C}$ to ${}^{13}\mathrm{C}$ ratio, and constrained the evolutionary status of TYC\,3251-581-1 based on the BaSTI stellar isochrones. The super Li-rich giant TYC\,3251-581-1 has $\mathrm{A}(\mathrm{Li})=3.51$, the average abundance of two lithium lines at $\lambda =6708$ Å and 6104 Å based on the non-local thermodynamic equilibrium (NLTE) analysis. The atmospheric parameters show that our target locates on the luminosity function bump. The low carbon isotopic ratio (${}^{12}\mathrm{C}{/}^{13}\mathrm{C}=9.0$), a slow rotational velocity $v\sin i=2.2{\mathrm{km}\mathrm{s}}^{-1}$, and no sign of IR excess suggest that additional mixing after first dredge up (FDU) should occur to bring internal synthesized Li to the surface. The low carbon ($[\mathrm{C}/\mathrm{Fe}]\sim -0.34$ ) and enhanced nitrogen ($[\mathrm{N}/\mathrm{Fe}]\sim 0.33$) are also consistent with the sign of mixing. Given the evolutionary stage of TYC\,3251-581-1 with the relatively low ${}^{12}\mathrm{C}{/}^{13}\mathrm{C}$, the internal production which replenishes Li in the outer layer is the most likely origin of Li enhancement for this star.

arXiv comment7 pages, 6 figures, accepted for publication in A&A

References in corpus (39)

• The chemical composition of the Sun
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones
• Elemental Abundance Survey of The Galactic Thick Disk
• Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program.Galactic stellar populations and planets
• Departures from LTE for neutral Li in late-type stars
• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• Thermohaline instability and rotation-induced mixing. I - Low- and intermediate-mass solar metallicity stars up to the end of the AGB
• The accretion of planets and brown dwarfs by giant stars -- II. solar mass stars on the red giant branch
• A new alpha-enhanced super-solar metallicity population
• Chemical abundances of 451 stars from the HARPS GTO planet search program: Thin disc, thick disc, and planets
• Systematic non-LTE study of the $-2.6\le$ [Fe/H] $\le 0.2$ F and G dwarfs in the solar neighbourhood. II. Abundance patterns from Li to Eu
• Origin of lithium enrichment in K giants
• Rapidly-rotating lithium-rich K giants: The new case of the giant PDS365
• Observable Signatures of Planet Accretion in Red Giant Stars I: Rapid Rotation and Light Element Replenishment
• On Lithium-Rich Red Giants. I. Engulfment of Sub-Stellar Companions
• On a Rapid Lithium Enrichment and Depletion of K Giant Stars
• Lithium-Rich Giants in Globular Clusters
• Lithium-Rich Field Giants in the Sloan Digital Sky Survey
• Old puzzle, new insights: a lithium rich giant quietly burning helium in its core
• The AMBRE Project: Constraining the lithium evolution in the Milky Way
• Lithium-rich giants in the Galactic thick disk
• Deep Mixing in Evolved Stars. II. Interpreting Li Abundances in RGB and AGB Stars
• Galactic Chemical Evolution: the Impact of the 13C-pocket Structure on the s-process Distribution
• Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters
• 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
• A super lithium-rich red-clump star in the open cluster Trumpler 5
• The Super Lithium-Rich Red Giant Rapid Rotator G0928+73.2600: A Case for Planet Accretion?
• On Infrared Excesses Associated With Li-Rich K Giants
• Lithium abundances along the RGB: FLAMES-GIRAFFE spectra of a large sample of low-mass Bulge stars
• Spectroscopic Study of IRAS 19285+0517(PDS 100): A Rapidly Rotating Li-Rich K Giant
• New extended atomic data in cool star model atmospheres - Using Kurucz's new iron data in MAFAGS-OS models
• Carbon abundances of the reference late-type stars from 1D analysis of atomic C I and molecular CH lines
• TAPAS - Tracking Advanced Planetary Systems with HARPS-N. II. Super Li-rich giant HD 107028
• Mass Outflow and Chromospheric Activity of Red Giant Stars in Globular Clusters II. M13 and M92
• On Lithium-Rich Red Giants. II. Engulfment on the Giant Branch of Trumpler 20
• Complex Organic and Inorganic Compounds in Shells of Lithium-rich K Giant Stars
• The Cool Giant HD 77361 - A Super Li-Rich Star

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